fixed a memory leak in class Hash<>,
added source file name to MP_ASSERT macro,
added exponential number format support to mpConvertToFloat()
added exponential number format support
added toString() to AST elements for testing,
some minor fixes/improvements
struct ASTElement -> class ASTElement,
getArguments() -> getArgumentsCount()
added more options and error codes,
added error messages,
error message, error position, JIT log, RPN string and DOT graph now can be stored in the Expression object
changed log output in mpCompileFunction(),
fixed function pointers for C++ compiler
numerous bugfixes!
added operator associativity,
unary operators now actually work,
added more error codes
added optimization of Block, Function Call, and Transform nodes,
added optimization of var*0, var+0, var^1, etc.
more tests, more output
Merge pull request #1 from Zueuk/doublepresso

Numerous bugfixes