Export to LocConnect and export to XLIFF are duplicated code

## Bug

It seems that there are two different sets of functions written to deal with exporting XLIFF to LocConnect, and exporting XLIFF to a file.

This has also resulted in duplicated bugs, such as `<group>` appearing in incorrect places in the XLIFF file (logged as separate bug #4).
## Solution

Merge the code for both scenarios to simplify.
