Change makeshift_root to local & escaped variable
Add option to run makeshift on bufenter
Implement automatic switching to working dir.
Extract change dir logic into s:set_makedir
Merge remote-tracking branch 'dseuss/master' into 0.11.0
Improve documentation
Release 0.11.0

- Automatic chdir [addresses #11], with thanks to @dseuss.
- Improve documentation