Have C Functions be stored in sheets, rather than globally.

[drwhut]

This way, when we get around to having Decision shared library files (i.e. dll, so), it can just return a Sheet with the C functions defined in it.

[drwhut]

This would also mean the way to call C from Decision (without using shared libraries, which will be implemented later), would change:

• Create a blank sheet in C.
• Populate it with the C functions you want.
• Load the Decision script, with the previous sheet already in it's include list (will have to implement a way to do this).
• Profit.