Added ptrint type
Core functions are now collected by Module
memfree and memalloc are explicitly set if available
'core util' is now in charge of the string type and memory managment
os uses ptrint to interface with c strings
Removed the now redundant string module
Removed unnecessary type casting
Pointer types can now have tags
Improved (if only a little) the error reporting for bad function calls
Array types are now global
Exposed the execution engine
Fixed a bug where type casting invalid call nodes would cause a crash
Importing modules no longer pollutes the local name space unnecessarily