Merge pull request #6 from Choups314/master

Fix compilation for Linux
Added difficulties, startup menu, key customizing, config file to save those latters
Updated n2DLib
Fixed delay on GS calcs
Store all settings in config file
Made startup menu more readable
Fixed Pattern_1_13 and 14
Started working on wave 11, implemented death dependancy on jointed enemies, fixed bug with dead jointed enemies
Fixed positionning bug
Fixed positionning bug with jointed dead enemies
Removed useless code
Completed Pattern_1_13 and 14, added Pattern_1_19 and 20
Added death dependency on jointed enemies in level stream
Finished chapter 1 level stream, added relevant patterns
Started working on boss suppor
Fixed bullets hitbox
Up
Added preliminary support for 'Dot eater' achievement
Fix stupid mistake
Fixed laser hitbox