Implement -dtags-to-keep and -dtags-to-remove commandline options (issue 149650043 by address@hidden)

[marc]

https://codereview.appspot.com/149650043/diff/1/Documentation/usage/running.itely
File Documentation/usage/running.itely (right):

https://codereview.appspot.com/149650043/diff/1/Documentation/usage/running.itely#newcode680
Documentation/usage/running.itely:680: @item @code{tags-to-keep}
What do you think about
@code{keep-with-tag} and @code{remove-with-tag}
to match the corresponding @code{\keepWithTag} and @code{\removeWithTag}
LilyPond commands?

Giving similar functions different names would at least confuse myself
as a user ;-)

https://codereview.appspot.com/149650043/