Preference or avoidance per language type (hearing impaired, foreign only)

[getzze]

closes #535
partly solves #925

Currently, we can only choose to prefer hearing impaired subtitles (among subtitles with the same highest score) with the "-hi" option. This PR adds the following:

• Add cli option "-HI" to prefer non-hearing-impaired subtitles, negation of existing "-hi".
• Add cli options "-fo" and "-FO" to prefer (or disfavor, respectively) foreign-only/forced subtitles.

"-hi" takes precedence over "-fo" and "-FO" (it cannot be used with "-HI").
"-fo" takes precedence over "-HI" (it cannot be used with "-FO").
Using "-HI" and "-FO" together is redundant and equivalent of using just one of the options.

However, not all providers are reporting foreign_only tags for subtitles (added opensubtitles.com support in this PR).

Other:

• Rename "forced" to "foreign_only" from Add subtitle language_type and Embedded subtitle subclass #1148

[getzze]

Also I didn't modify the scores, I will do it in another PR when adding an fps match.