More icons. At last!
made document data available to filter parser
implemented use of predefined filters
added filter text column to filter table
allow colons in names (filter)
Adding .directory to gitignore.
Delete .directory
fixed broken record deletion
avoid use of column number literals
update tables on filter record changes
improved one-shot filter handling; allow empty pre-defined filters
Merge remote-tracking branch 'sirherrbatka/icons-svg'

Conflicts:
	.gitignore
Refactored loading screen

 - Add loading progress for data files, global map, terrain
 - Refactored and improved cell loading progress
Renamed Terrain::Terrain to Terrain::World to make VC happy
Replaced log2 to make VC happy
Fix the water being affected by fog on the map
streamlined filter syntax
Avoid a hack to play the underwater sound properly
Store the underwater sound to easily stop it
Slightly randomize time between environment sounds

We should use the "Minimum Time Between Environmental Sounds" and
"Maximum Time Between Environmental Sounds" INI/fallback settings, but we don't
have them.