Implement #Save and #Restore for variables, settings, and env vars
Use value#Save and value#Restore in maktaba#system
Fix bad regex matching on substrings in value#Save and #Restore
Merge branch 'master' into value_save

Conflicts:
	autoload/maktaba/system.vim
Update stale docs
Add #SaveAll() for list of variables, and make #Save take single string
Bump version to 1.4.0
Merge pull request #58 from google/value_save

Add maktaba#value#Save and maktaba#value#Restore