[Feature] Linux spellchecker support for regional variants of English

[hexadecimalDinosaur]

The ability to add custom Hunspell dictionary files on Linux and having en_CA and en_AU dictionaries added to the typora/dictionaries repo and spellcheck options would be greatly appreciated.

Canadian English combines and accepts both American and British variants and adds some uniquely domestic spellings and as such it is frustrating to be forced to use the American or British dictionary which results in many false positives for spelling mistakes.