Similar to the perl/tk's build structure, this 'mTk' directory 
contains _complete_ sources of Tktable in their minimally modified forms.

This is because 'munging' to pTk directory from either modified form
or original Tk becomes very complex now Tk is split unix/generic.

It should also makes merging changes less error prone.

# Note that as for Tk800 and Tk804 compatibility, there are two directories here
Tktable: Main-line TableMatrix code for Tk804 and above
Tktable800: Tablematrix code compatible with the older Tk800-series.
