Add standard accelerators on Windows

[rjkroege]

On windows, ctrl-{z,x,c,v} are shortcuts for undo, cut, copy, paste.
Edwood did not implement this. Add these shortcuts.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.

Project coverage is 58.48%. Comparing base (8eb4bb3) to head (07e33a4).
Report is 1 commits behind head on master.

❗ Current head 07e33a4 differs from pull request most recent head 2d2b7b0

Please upload reports for the commit 2d2b7b0 to get more accurate results.

Files	Patch %	Lines
text.go	0.00%	4 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #497   +/-   ##
=======================================
  Coverage   58.48%   58.48%           
=======================================
  Files          54       54           
  Lines       10761    10761           
=======================================
  Hits         6294     6294           
  Misses       4032     4032           
  Partials      435      435           

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