Use g_file_set_contents() to write files to disk in utils_write_file() for better error checking and to avoid corruption of config files when there is no more free disk space.
This is not used for saving documents (part of Debian bug #503391).

git-svn-id: https://geany.svn.sourceforge.net/svnroot/geany/trunk@3507 ea778897-0a13-0410-b9d1-a72fbfd435f5