Better name for dictionary merge

Merging is more obvious naming than conflict.
Improve import code readability
Skip fuzzy entries from import unconditionally

This functionality was never used by frontend code.
Configurable merging of upload

User can choose merging method - add translation, suggestion or fuzzy
translation.

Currently only translations and fuzzy translations are implemented.

Part of issue #214
Consistent coding style
Implement merging as suggestion

Currently we don't check for existing ones, but simply create new one in
all cases.

This is part of issue #214
Coding style