Some errors for gregorio print to stderr but do not write to glog.  This leads to the error being lost when autocompiling, so we add a redirect which will capture the stderr output and put it in glog.

When compiling gabc files, tmp-gre will be created in the cwd and gtex and glog files will be written there.  This allows for compilation of gabc files which are outside the current tree and should allow for compilation of tex files from outside outside of the project folder.