refactor compiler structure

[aripiprazole]

• move parser module to syntax #35
• rename compiler folder to frontend #39
• remove codegen module #37
• remove llvm4k module #20
• remove cli module #44
• implement a IR #36
• remove parser ambiguities #53
• implement new backend #34
• use query based architeture #49
• refactor type system #50
• implement new frontend cli #46