Add 'Find in selection' option for "Find and Replace" dialog

[Dumluregn]

Type of report

Feature request

Provide description of the new feature

Currently the editor searches the whole content (or, if Match cyclic option is off, from the beginning of selection to the end of document). It could be useful to be able to only find (and replace) items inside the selection.

As for the size estimation, I think it's somewhere between M and L.