Revamped display antialiasing options into filters

[SpookyIluha]

• The current display options include "anti-aliasing" settings that are cryptic and don't match expectations, this PR fixes any confusion about what is actually happening to the output with selected display filtering options.
• This PR changes and deprecates antialias_t (used only in display_init) into filter_options_t with similar options (deprecated AA options are mapped to them directly) and verbose comments, explaining each filter.
• filter_options_t is an enum with only valid and useful filtering options, such as resampling, AA and de-dithering.
• Also updated gamma comments to better illustrate their use-cases.

[rasky]

Thanks Spooky, this looks like a fantastic improvement and the new vi.h is a very good step in the direction of having a real VI library at some point.

Note that doxygen is failing, please have a look at the CI failures. We need to fix those before merging.

Also please rebase the branch on latest trunk, as I want to use the rebase-merge strategy.