Create branch to split out a GeanyEditor struct type for use in editor.c with…

Create branch to split out a GeanyEditor struct type for use in editor.c with fields from GeanyDocument.

git-svn-id: https://geany.svn.sourceforge.net/svnroot/geany/branches/editor-struct@2762 ea778897-0a13-0410-b9d1-a72fbfd435f5