Feature/fill circle

[abhaysp95]

Feature request done for issue 48

Changelog:

• Ability to set general.accessibility in config.toml file for viddy
• Change to fill circle upon setting on the option of Suspend, Diff, Bell when accessibility is set to true
• And change the foreground color to black and background color to white (for better contrast)
• If accessibility is set to false, viddy behaves as it did before

[sachaos]

@coolabhays Thank you. Accessibility mode is great.
I consider it enough to start with that it will be a filled circle.
I would like to avoid changing the foreground color to black and the background color to white because it conflicts with the theme setting.

[sachaos]

@coolabhays I want to merge this.
If there is no comment here in 3 days, I would like to fix and merge this PR

[abhaysp95]

@sachaos Yes, changing foreground and background color to black and white does stands out from the theme, but since this was for accessibility setting, it was not so bad payoff. Also, since there are different types of colour-blindness, white-black combination seemed a pretty valid choice.
Also, mention the usage (maybe in wiki for viddy) all the different color value settings like you used for viper configuration under [color], as going through code I wasn't sure, like what's secondary_text, tertiary_text, graphics etc., as it would help in using them in development.
The color combination of for diff which is I think [white:green]' by default, is also not a good combination for colour-blindness.

What I think is that accessibility should be a toggle switch, which should set necessary settings on the little payoff for the theme (which will not be of much usage for them anyway). Do tell what do you think ?