Add config parser and tests
Add parser for game configurations and test cases
Rewrote game system and adapted all other subsystems to it. Still has some bugs, but overall it works better than before.
Fixed some compiler warnings and linker errors
Preferences store their paths as IO::Path instances instead of strings
Switch to wxWidgets 3.0
Add welcome dialog

Signed-off-by: Kristian Duske <kristian.duske@gmail.com>
Welcome dialog is now a frame.
Hide welcome dialog when the user creates a new map or loads an existing map
Add a better dialog for creating new documents
Don't show the map frame before the game selection dialog is done when creating a new document
Change the new document dialog so that it can be reused to select the game for an existing document
Add missing files for game selection dialog
Some cosmetic changes