Add color support for messages

This commit contains some dummy message functions (_type).
They are intended to be removed in a later commit
Overload message functions

… and get rid of those ugly “_type” things
Overload player.cpp wrappers around add_msg
Ensure new game_messages have always a type.
Change enum game_message_type
Put most game messages (add_msg …) into an appropriate category
Make new NPC wrapper functions around add_msg (with type)
Colorize melee battle messages
Colorize death and guilt messages
Colorize mutation messages
Colorize monster messages
Fix flipped message colors for mutation changes
Document “enum game_message_type” in ENUMS.md
Categorize messages related to inventory letters
Small fix regarding default game message type
Clean up redundant code
Add back a lost string
Merge remote-tracking branch 'dda/pr/7471' into dda-master

* dda/pr/7471:
  Add back a lost string
  Clean up redundant code
  Small fix regarding default game message type
  Categorize messages related to inventory letters
  Document “enum game_message_type” in ENUMS.md
  Fix flipped message colors for mutation changes
  Colorize monster messages
  Colorize mutation messages
  Colorize death and guilt messages
  Colorize melee battle messages
  Make new NPC wrapper functions around add_msg (with type)
  Put most game messages (add_msg …) into an appropriate category
  Change enum game_message_type
  Ensure new game_messages have always a type.
  Overload player.cpp wrappers around add_msg
  Overload message functions
  Add color support for messages

Conflicts:
	src/bionics.cpp
	src/defense.cpp
	src/game.cpp
	src/iuse.cpp
	src/messages.cpp
	src/monattack.cpp
	src/mondeath.cpp
	src/player.cpp
Merge remote-tracking branch 'dda/master' into dda-master