Ignore backup files and VIM .swp files
Trim brackets after return
Unconditionally split a group if it takes the form [a,...,a,b,...,b]
Optimize code a little bit
Add -d (--diff) to tests.py
Add test "togb18030"
Update tests.py

* Add test names.
* User can now specify a list of tests on command line
Fix ExprTable.statics. It was VERRRRRRY slow