BREAKING CHANGE: refactor library

[Disservin]

• split the shl into multiple files, which are combined back using a python script
• refactor various parts of the library, mainly the types like Bitboard, Square, File, Ranke, Piece, PieceType

BREAKING CHANGE:

• MoveGenType is now in the movegen namespace
• all utils functions have been removed/moved except of splitString. Functions like squareFile are now a member of Square
• basically all types have been made classes with member functions.
• MAX_SQ and MAX_PIECE constants have been removed
• builtin intrinsic functions have been made a member of the Bitboard class
• probably various conversions will now fail and require explicit casts, where before the enum was casted to an int/boolean