convert: use flattened list for generating structs
convert: order columns, then process them -> separate loops
convert: added subdata column type description
convert: added first bunch of field exports for subdata columns
convert: added primary key link for sound export
ci: installing sound libaries: libopusfile, libopus and libogg
ci: added libogg source compilation, ubuntu is outdated again...
ci: use subshells for dependency source compilations
ci: enabled running test cases after build
testing: run all tests independently, show summary afterwards
engine: now using hashmap for storing terrain chunks
game: fixed random range function and renamed sound variables
engine: implemented operand-templated modulo function
engine/terrain_object: comments indented correctly
engine/terrain_object: implemented basic underground terrain checking
engine/terrain: comment for draw function fixed
game: terrain initialisation size definition as constexpr
engine/terrain: fixed using 2 map queries for getting chunks
engine/terrain: another hash function for chunk coordinates
Merge branch 'master' into convertdat

this mainly fixes the travis build