Backport recent changes from Scintilla CVS to add partial support for RFC2822 styled text using the Properties lexer.
Ignore leading whitespace for config files and RFC2822 text.

git-svn-id: https://geany.svn.sourceforge.net/svnroot/geany/trunk@3669 ea778897-0a13-0410-b9d1-a72fbfd435f5