add `--ignore` option to `sh-to-mod` sub-command

[xdelaruelle]

source-sh modulefile command has a --ignore option which enables to specify some environment changes to withdraw. It would be interesting to also have this option on the sh-to-mod sub-command to also filter environment changes there.

[xdelaruelle]

Such feature could easily be added:

• call parseSourceShArgs from cmdModuleShToMod like done in source-sh procedure
• enable --ignore argument to go from the command line to cmdModuleShToMod
  • add it to parseModuleCommandArgs
  • add it to main option parse switch