Validate language field #1344
Description
Right now, you can type anything you want in the Language field, including asdf. It's only supposed to contain a comma-delimited list of ISO-639 codes, each with an optional ISO-3166 country code.
List of languages in the DB now
+-----------------+-----------+
| language | count(id) |
+-----------------+-----------+
| en | 11744 |
| NULL | 778 |
| es | 594 |
| fr | 447 |
| de | 269 |
| it | 191 |
| en-US | 157 |
| ru | 80 |
| cs | 79 |
| ja | 44 |
| en-GB | 42 |
| en, fr | 41 |
| en, es | 39 |
| sv | 30 |
| sk | 23 |
| english | 21 |
| zh-CN | 20 |
| zh-Hans | 18 |
| en, ru | 16 |
| pt | 16 |
| nl | 13 |
| pl | 11 |
| hu | 11 |
| es, en | 10 |
| pt-BR | 10 |
| en-CA | 10 |
| fr, en | 9 |
| en, it | 8 |
| en, pt-br | 8 |
| sl | 8 |
| sr | 6 |
| en-UK | 6 |
| ca | 5 |
| eo | 5 |
| en-AU | 5 |
| zh-cmn-Hans | 5 |
| da | 5 |
| de, en | 5 |
| zh-cmn-Hant-TW | 5 |
| zh-Hant | 4 |
| no | 4 |
| ko | 4 |
| hr, sr | 4 |
| ru, en | 3 |
| el | 2 |
| ro | 2 |
| ms | 2 |
| en, de | 2 |
| zh | 2 |
| bs | 2 |
| en, zh-cmn-Hans | 2 |
| en, ja | 2 |
| en, nl | 2 |
| English (en) | 2 |
| de, en, es | 2 |
| zh-Hans, en | 2 |
| es-AR | 2 |
| en-IN | 1 |
| de, en, es, ru | 1 |
| es-ES | 1 |
| es,en,ja | 1 |
| en, ja, ru | 1 |
| ar-sa | 1 |
| bn | 1 |
| en,fr,it | 1 |
| en, mis | 1 |
| hr, sl, sr | 1 |
| de, en, pt, ru | 1 |
| Users Choice | 1 |
| en, pl | 1 |
| rus | 1 |
| ja, en, ru | 1 |
| en,fr,it,uk,es | 1 |
| cs, en, pl | 1 |
| Toki Pona | 1 |
| Danish, da | 1 |
| en, sco | 1 |
| en, pt | 1 |
| pt-BR, en | 1 |
| da-DK | 1 |
| tok, en | 1 |
| en-US, iu | 1 |
| C# | 1 |
| en, uk | 1 |
| en, ru, zh | 1 |
| de / en | 1 |
| en, es, ca | 1 |
| fr, it | 1 |
| ca, es | 1 |
| en,es | 1 |
| en, ko | 1 |
| ja,en | 1 |
| de,en,es,fr,zh | 1 |
| id | 1 |
| de, en, fr | 1 |
| it, en, fr, es | 1 |
| zh-Hant, en | 1 |
| ja, en | 1 |
| en-NZ | 1 |
| nl-BE | 1 |
| en,ja,pt,de,it | 1 |
| en, hu | 1 |
| en, zh | 1 |
| en,es,eo | 1 |
| en, sk | 1 |
| en, pt, ru | 1 |
| en, fr, ru | 1 |
| el, en | 1 |
| hr | 1 |
| en, es, zh-Hant | 1 |
| en, tr | 1 |
| en,fr | 1 |
| hr, sl | 1 |
| en, es, fr, tr | 1 |
| ru,en | 1 |
| en, es, ru | 1 |
| is | 1 |
| en, zh-yue-Hant | 1 |
| it, en | 1 |
| en, nl, de | 1 |
| en,ja,fr,de,es | 1 |
| de,en,es,fr,tr | 1 |
| en,de,es,ru,uk | 1 |
| nl, en | 1 |
| fi | 1 |
| en, es-AR | 1 |
| en,ru,eo | 1 |
| en, hu, uk | 1 |
| fr,en,zh-CN | 1 |
| Spanglish | 1 |
| en, es, it | 1 |
| sco | 1 |
| en, es, zh, + | 1 |
| it, en, sk | 1 |
+-----------------+-----------+
Skimming through the list, these catch my eye:
+-----------------+-----------+
| language | count(id) |
+-----------------+-----------+
| NULL | 778 |
| english | 21 |
| zh-CN | 20 |
| zh-Hans | 18 |
| zh-cmn-Hans | 5 |
| zh-cmn-Hant-TW | 5 |
| zh-Hant | 4 |
| en, zh-cmn-Hans | 2 |
| English (en) | 2 |
| zh-Hans, en | 2 |
| bn | 1 |
| en, mis | 1 |
| Users Choice | 1 |
| rus | 1 |
| Toki Pona | 1 |
| pt-BR, en | 1 |
| da-DK | 1 |
| tok, en | 1 |
| C# | 1 |
| de / en | 1 |
| zh-Hant, en | 1 |
| en-NZ | 1 |
| nl-BE | 1 |
| en, es, zh-Hant | 1 |
| en, zh-yue-Hant | 1 |
| Spanglish | 1 |
| sco | 1 |
| en, es, zh, + | 1 |
+-----------------+-----------+