v0.16: Better items UI, rewards window help, balancing

This update is primarily based on feedback given by playtesters on Discord and this forum.

Item boxes in reward window and entity list now display item effects, removing the need to look at each item's hint.
Rewards window now has help/tutorial, accessible by pressing '?' icon in top right corner.

Minor gameplay changes:

• New ascension: Card upgrades are limited to 6
• Added 3 more quest-related achievements

Major UI changes:

• Added keyboard controls for playing cards and selecting hero
  • Toggled by 'Keyboard controls' settings, off by default
•   Item elements in rewards and item list are now larger and display descriptions directly
  •   'Compact items' setting makes item reward elements smaller again

Minor UI changes:

• Centered monsters and items vertically
• Some status icons and values re-styled to be more distinctive
• Added help explaining elements of rewards window
• Improved some card images
• Optimized rendering on slow Internet connections
• Text filter in entity lists now accepts 'property=value' syntax, e.g. 'cost.hp=3'
• On restart, pre-select last played hero

New cards (2):

• Liturgy, Explosive Arrow

New items (3):

• Model of the Spire, Scabbard, Kaleidoscope

New monsters (2):

• Thug, Troll Berserker

New quests (5):

• Old temple: Fail a ritual
• Scenic vista: Watch a rainbow
• Castle: Perfect sword drawing technique
• Art fair: Collect colored glass beads
• Bandit hideout: Beat them in the brawl

Balance and miscellaneous changes:

• Reworked card: Push
• Nefed cards: Second Wind
• Nerfed items: Quiver, Deformed Coin
• Nerfed monsters: Suspicious Chest
• Renamed 'Grove' quest location to 'Scenic vista'

Selected bugfixes:

•   Fixed deducting money for clicking 'upgrade' even if card is not upgradeable
•   Fixed item size responsiveness on small screens
•   Fixed: target enemy changed when enemy in front dies
•   Fixed hang when ending turn while the card is still playing
•   Fixed target display for redirected effects