Add new pref: lineWiseCopyCut

[marcelgerber]

For #9311. Adds a new pref lineWiseCopyCut (still enabled by default) to suppress copy/cut from copying/cutting a whole line when there's no selection.

See also http://codemirror.net/doc/manual.html#option_lineWiseCopyCut.

[le717]

I don't think this is quite the issue reported. The problem was not whole-line cut/copy as a feature, but that it copy/pastes a totally blank line when used on a blank line. The desired fix was for it to not activate at all on blank lines. The issue, as I already detailed, is the "\n" CodeMirror always adds to the end of the copied line. With those removed (more like added only under proper circumstances), using whole-line cut/copy on a blank line works as desired (and also as I said, remedies a number described in #9130).

EDIT: I could be reading this all wrong and this PR does exactly what needs to be done instead of completely disabling the feature (as I initially thought). Apologies if that is the case. :\

[marcelgerber]

This actually is what you think it is.
The pref, when disabled, disables the whole copy-line-where-cursor-is-on feature.

Even though this may not be the exact solution to the referenced issue, I guess it is a step in the right direction either way.

[ficristo]

This options seems useful to me. I like this.
/cc @swmitra @nethip

[Denisov21]

Good idea for me!

[M4TH76]

That would really help me, I often accidentally blind type Ctrl-C instead of Ctrl-V

[ficristo]

LGTM, but the description is not correct: is not only about empty lines.

[marcelgerber]

Argh, now it's back to almost exactly the wording the CM manual uses.

[ficristo]

Thank you, LGTM.

[marcelgerber]

Thank you for reviewing!