Fields can be unloaded with a file-extension
Files with extension can be uploaded

The extension is stripped from the filename
Return nil, when current field has no extension set
Version bump to 1.2.0

Feature: field-extensions
Cache config-file and database-connection

Uncommited changes in those files would be removed by the
'git stash'-command.
By preloading the config-file, and executing a dummy-query, those
changes would still be used
Version bump to 1.2.1

Features: preload config-file and database-connection
test
remove test
Also test for the possibility it happens