CC41 RPN Calculator

[Craig Bladow]

v0.45.01 alpha can now be downloaded from the GitHub link in the first post or in my signature below.

Many thanks to Allen for letting me know about issues with DEC and OCT.

Changes in this release include:
OCT and DEC changed to return DATA ERROR for non-integer input and leave the X register unchanged.
OCT and DEC changed to allow conversion of negative numbers.
DEC changed to return DATA ERROR for input containing digits 8 and 9 and leave the X register unchanged.
OCT and DEC changed to return DATA ERROR for inputs greater than 281,474,976,710,655 for OCT and 7,777,777,777,777,777 for DEC.
MOD function revised from C math libray % behavior, now matches HP-41CX behavior for negative operands.
RND function fixed regression so RND uses calculator precision. Added RND to regression tests.
Rounding in SCI and ENG display modes implemented.
X<>F changed to return DATA ERROR for values greater than 255.