Add option to ignore common leading articles in Filename sort

[PhilaPhan80]

Hello, everyone. A new enhancement has been merged into the emulationstation-dev package!

Feedback and test results are greatly appreciated.

This enhancement adds an option called Ignore Articles (Name Sort Only) to the START menu. When enabled, common leading articles are ignored in both ascending and descending order while sorting each system's game titles, similar to popular multimedia-based systems. The comma-delimited list of articles is stored within the es_settings.cfg file as LeadingArticles. By default, common English articles "a", "an", and "the" are ignored, and others may be added to the list manually. (This also allows more articles to be easily added to the default setting going forward.) The option itself is persisted as IgnoreLeadingArticles.

Additionally, a popup message is displayed whenever sorting has been re-performed in response to the selection above.

Examples:

[SortType = FILENAME ASC, IgnoreLeadingArticles = false]

A Boy and His Blob
Adventures of Lolo
Marble Madness
The Legend of Zelda
Yoshi's Cookie

[SortType = FILENAME ASC, IgnoreLeadingArticles = true]

Adventures of Lolo
A Boy and His Blob <-- article ignored
The Legend of Zelda <-- article ignored
Marble Madness
Yoshi's Cookie

More detailed technical information is listed within the pull request:

https://github.com/RetroPie/EmulationStation/pull/729