added consts
changed loops to pre-increment
working on C++ error system
working on c++ utility functions
macro now works.
factoring out c++ into seperate files.
added header file
movec concat to a seperate file.
replaced seq along with seq len
fixed syntax error
minor tweaks
added an early implementation of c++ call handling
updated news
fixed bad name in xdo
added collection length checking macro
updated news
fixed an index bug in xGroupBy
corrected zips name handling
fixed a bad precondition in is_na
fixed an improper test in xFold