Incorrect menu spelling for `StandardUncertainty` and several other commands

[c3d]

The menu shows StdUnc, but the actual short spelling is CstSU. User @Wiljea was clearly confused by this since he tried to use StdUnc in a program. There are a number of other commands that have the same problem.

[c3d]

This has been implemented.

Commit: 99306c0d
Release: 0.9.17

Closing as fixed.