Refactor white space tests factorized to share a common setup.
Add test to ensure parser recognise litteral constant declaration as a primary expression.
Correct return type of the Parser::parseTopLevelExpr() method from ExprAST* to FunctionAST* since it has to return a function (meemaw is an expression based language).
Refactor the parser architecture to add the primary expression concept.

Primary exception and top level expression are now distinct and documented concept via the parseTopLevelExpr() and parsePrimaryExpr() method in the Parser class.
Correct the test about litteral constant declaration being a top level expression. The end of the test was not valid (stupid copy-paste from float litteral test).
Add parser code to support litteral constant declaration as top level expression.
New uncrustify config to force braced blocks in every control structure.
Cleanup whitespace and code formating according to new uncrustify config.
Refactor parser by splitting it in parser (parser.h/cpp) and ast nodes (ast.h/cpp) because the files were really too long to handle easily.