added pre-run cleanup

failed or incomplete runs will leave `/tmp/submodules.txt` laying around, which causes the next run to assume the last selections for potential submodules. This pre-run cleanup ensures we start fresh

Author: Jared Murrell

svn2github.sh

@@ -2,6 +2,7 @@
 INC_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd)"
 source ${INC_DIR}/_functions.sh
 
+_cleanup
 _welcome
 _setup
 _svn_sizer