Update changelog for v0.4.9.0
Update .cabal and documentation
Make consumables more common and other content tweaks
Merge equivalent items and show the first found item

by the particular client. In particular, the level recorded
will be the one the item was first found on.
Add one more healing potion
Simplify item number per level specification
Add a Makefile command to build a binary
Fix haddocks and refactor the Speedup family
Balance caves and their places
Tell apart floor and ground fence types
Add more light source items to ambush game mode
Make the noise cave easier to explore
Start battle mode games with weapons
Generate more enemies in battle mode now that heroes have weapons
Rename summonable to mobile
Avoid immobile actors except in campaign
Make the battle terrain easier to defend
Make potion of glue identified
Quantize some aspect values, to combine items easily
Make weapons rarer but stronger