Added dynamic languages via command

- Use -nominatim-import-languages command with comma separated
languages to load those languages during import
- Use -nominatim-import-languages command with comma seperated
languages to use certain languages during run

Example: -nominatim-import-languages en,de,nl
Fix invalid json
Seperated language commands for import/running

Use -nominatim-import-languages for importing and -supported-languages
for runtime languages
Added dutch (nl) to mappings.json
Added stripNonDigits util
Fixed ImporterTest to use (static) languages
Added postcode check for nl postcodes

- Filter doubles out if there are highways with the same name &
postcode numbers when language is 'nl' (i.e. the same street has 6532RA
and 6532BE, which should only be returned once to prevent clutter in
autocomplete)
Fixed tests to use new lang scheme
Added Netbeans xml to .gitignore
Reverted string lat/lon back to doubles
Deleted language specific obj from mappings.json
Use mappings template & add lang specific strings
Removed spaces
Unified commandline param to 'using-languages'
Modified test with static lang
Reverted NL postcode check

- Should be submitted as separate PR
Removed commented code
Renamed commandline arg to just '-languages'
Refactored mappings.json code
Some refactoring