New version release - list of changes, new features and bug fixes

* Fixed bug in companion AI. An error in the code made NPC's jump around rather than walking tile by tile when trying to heal. Should now be working properly.

* Finished hold person spell. On a failed wisdom save, replaces the AI with a held person AI for 20 turns or until they make a successful wisdom save. Available for all clerics and as for testing purposes on premade Human Wizards.

* Fixed bug where I forgot to make flaming sphere cause damage.

* Fixed bug where player can kill themselves with a spell area of effect, and double their XP as a result.

* Fixed bug in companion AI where still tried to path to player after they were dead.

* Finished invisibility spell. Applies a condition to caster or another creature within touching distance which lasts 100 turns and prevents all other creatures from seeing them. Creatures with the blindsight trait can still sense them. Gives advantage to an attacker who attacks whilst invisible against an unaware creature. Changed attack function to remove invisibility condition upon any attack. Changed spell function to remove condition upon casting as well. Doesn't take into account magical detection abilities but they don't exist in-game yet.

* Updated opportunity attack function to make invisible creatures not take these. It cancels invisibility automatically and that's probably not something that I want people to have unwittingly happen.

* Updated UI to show whether proficient or not in equipped armour and shields.

* Fixed bug where creatures were taking opportunity attacks against unseen actors.

* Updated display functions to take into account hidden and invisible monsters.

* Added the ability for items to have temporary conditions applied to them. Added a check for every turn to loop through all items on map and all items in all actor's inventories to make those conditions take a turn. A fair bit of extra complexity but necessary for temporary effects such as the magic weapon spell.

* Changed message system for expiring conditions to allow messages to be given to player for effects on items in player's inventory. It also works for items in sight on the ground.

* Updated UI to reflect changes to items with temporary conditions. Updated combat routines to deal with items with temporary conditions.

* Updated UI to show whether proficient or not with armour and shields equipped. This wasn't clear before because the only outcome was disadvantage when attacking, so now it's clear.

* Reworked torches and their illumination quality. It was previously a trait but that was a bad fit, and instead it's not a permanent condition like other enchantments and effects on items.

* Finished magic weapon spell. Lets player choose an item in inventory. Creates a new effect which adds +1 to hit bonus and +1 damage for 100 turns before expiring. Doesn't work on anything which isn't a weapon. 

* Finished misty step spell. Allows caster to teleport to any square within 6 tiles.

* Finished shatter spell. Area of effect damage 3d8 to anyone with 2 squares of target tile. Successful constitution save halves the damage.

* Finished web spell. Creates a new effect on each square within 2 squares of target. Web effect checks each turn for an actor on its location. If so, they must make a dexterity save. On fail, they are now 'stuck'. Stuck is handled by attaching a new condition to that actor which makes them make a successful strength saving throw before they are able to move. The duration of this condition is the same as the original effect, so they should both expire at the same time otherwise. Added checks to all move functions to account for this. 

* Added check for unconscious status to remove if hp ever goes above 0 for any reason. This will hopefully catch any odd instances where hp's are added somehow in a weird way.

* Finished aid spell. 2nd level cleric spell which lets you pick 3 creatures and boost their hp and max_hp by 5 for 8 hours. There seems to be some conjecture about what happens when the spell expires and you need those 5 hp to stay alive, so I've gone with the view that you get to keep the current hp but not the max_hp. This avoids any of those weird scenarios.

* Finished lesser restoration spell (for now). Touch effect to remove a range of harmful conditions. The only one that exists in game right now is being poisoned, so it just cures that. Will need to revisit for deafness, blindness, and paralysation. 

* Finished prayer of healing. 2nd level cleric spell which heals up to 6 creatures in sight of 2d8 plus wisdom bonus of HP.

* Finished spiritual weapon. 2nd level cleric spell which creates a new object on the map of the caster's faction which fights alongside the caster. The rules as written call for a high level of control over the weapon, but that didn't seem like fun so I gave it autonomy. It's effectively a flying sword with 100 HP (making it effectively indestructible) and with a to-hit bonus and damage bonus of the caster's wisdom ability modifier. 

* Created a new 'summoned' condition to apply to creatures which makes them disappear after a certain duration and made this apply to spiritual weapons. Can easily be extended to any kind of summoned creature imaginable. 

* Adjusted pathfinding to make allies slightly prefer going through doors rather than switching places with allied creatures.