RTF to HTML Lite Converter

I was converting an RTF file with lots of font changes; this caused a
segmentation error, due to a buffer overflow in a CRevString (closingtags).
As a temporary workaround, I just increased the buffer size in gstring.h
from 256 to 4096, but surely, there is a more appropriate and robust way to
deal with this issue.

I am also wondering if perhaps successive font changes should trigger the
closing of the previous SPAN tag, instead of opening an ever increasing
number of nested SPANs, which seems to have been at the root of the problem
that I ran into.