Using a thread for Find in Files on GTK

[Neil Hodgson]

The implementation of Find in Files on GTK has been changed to run on a background thread. Previously, a second instance of the SciTE program was run with the -grep command line parameter. The search string and other parameters were passed on the command line which could lead to problems when the parameters included shell-significant characters.

Performance appears similar to the previous implementation but I haven't examined that closely.

The -grep command line option and its consequences may be removed later.

There may be scope for merging the platform-specific implementations of the Find in Files thread into a more unified implementation.

The committed changes can be examined either in the repositories

   hg clone http://hg.code.sf.net/p/scintilla/scite

or from

   https://www.scintilla.org/scite.zip Source

Neil