extract generic spellchecking functionality from the full viewport function

Add get_typos(range) to retrieve a string of misspelled word in a specific file range
by calling the spellchecker's list command. It return nil or a string with each
misspell followed by a newline.

Introduce typo_iter(text, typos, ignored) to iterate over all not ignored
typos and their positions in text. It returns an statefull iterator function
closure. Which will return the next typo and ist start and finish in the text,
starting by 1.

0 files changed, 0 insertions, 0 deletions