Support more country specific transliterations

[Tazinho]

For example german: Ä -> AE; Ö-> OE, Ü -> UE, ä -> ae, ö -> oe, ü -> ue, ß -> ss

[Tazinho]

Danish doesn't seem to work, see:

> to_any_case(c("Æ", "Ae"), transliterations = "Latin-ASCII")
[1] "ae" "ae"
> to_any_case(c("æ", "ae"), transliterations = "Latin-ASCII")
[1] "ae" "ae"
> to_any_case(c("Ø", "Oe"), transliterations = "Latin-ASCII")
[1] "o"  "oe"
> to_any_case(c("ø", "oe"), transliterations = "Latin-ASCII")
[1] "o"  "oe"
> to_any_case(c("Å", "Aa"), transliterations = "Latin-ASCII")
[1] "a"  "aa"
> to_any_case(c("å", "aa"), transliterations = "Latin-ASCII")
[1] "a"  "aa"

All together:

• [X] German + tests
• [x] Danish + tests
• [x] Swedish + tests
• [ ] Norwegian + tests
• [x] Finnish + tests
• [ ] Icelandic + tests
• [ ] Faroese + tests
• [ ] Greenlandic + tests
• [ ] Czech + tests
• [ ] Dutch + tests
• [ ] Turkish + tests

Also Need to update the following files

• [ ] function documentations

• [ ] Readme

• [ ] News

• [x] Also need to allow users to specify a list of replacements. Done via named transliteration arguments.

• [ ] need to document the mappings here in a more transparent and structured way.

See discussions:

• http://forum.camendesign.com/language_specific_transliteration_re_transliteration
• https://github.com/cocur/slugify/commit/64af0ea4706a3eb5916b97b75f8da513a4e566ca