This is a rather stupid implementation as it does the search in linear
time. More importantly, it is correct and helps porting gcc. Besides, it
can easily be fixed in due time.
Removed Maxsi::Process:: functions as they suck and are barely used. Gave
the functions standard names and put them in their own source files.
The declarations now have nice noreturn attributes attached.
unsetenv(3), envlength(3), getenvindexed(3), and environ(7).
This provides the user-space foundation for environmental variables.
Note that this works over fork(2), but not execve(2) yet.
C and C++ files are now kept together and so are the mxmpp declarations.
Header files are now stored in include/ and mxmpp'd into preproc/.
All other code now -I ../libmaxsi/preproc.
And other stuff to make this happen, including refactoring Makefile.
