v1.15 - Lategame rebalance

I created new boards for the late-game fights to weaken stone-spamming strategies while improving freeze, burn, etc.

Mining Battles and 71-stone should also be more fun now, with an increased hand-size of 7.

Change List:

• Maximum hand-size increased from 6 to 7.
• You can right-click when using 3-stone to auto-discard your leftmost card.
• 29-stone now has a broader effect: "stays in hand [when played]" --> "cannot be discarded". 
• 29-stone is more likely to be used by tournament NPCs  (~10% --> ~20%).
• 71- and 91-stone sprites swapped for consistency (green=immune).
• Battle 71 / 79 / 83 / 89 decks and boards changed. (Bigger holes in the board to nerf stone-spam strategies.)
• 89-master nerfed (170 --> 150 energy).
• The 71-master no longer loves to play 98-stone for no reason.
• Mining puzzles M2 and M3 nerfed. (5-stone --> 2-stone, 10-stone ---> 5-stone)
• Pressing Esc in the main menu no longer quits the game in-browser.
• Lab logs are less wordy.
• Bug fixes and dialogue changes.

Planned changes for the near future:

• 47-stone "Discard lowest card" --> "Discard highest card"
• New designs for puzzle levels
• Swap 47 (discard) and 61 (cover)