0.0.1, 2011.10.18: based on XCALC 2.9.4 but completely rewritten in C++
0.0.2, 2012.02.06: Help implemented via html dubdirectory. Everything can be undone/redone. Better keyboard layout.
0.0.3, 2012.02.19: Several small fixes: BACK works. Still need a way to enter e.g. fractions in complex mode.
	   Dflt conversion from complax to real now skips imag part. If you want abs, do |x| first.
	   Root extraction (integer roots) better.
	   No more sigaction - signals never worked, and results are inf/nan as appropriate instead.
