Enhancement: Don't use global preference files

[damccull]

Currently the plugin overwrites the 'theme' and 'color_scheme' settings of the Preferences.sublime-settings (User) file in order to switch themes and color schemes.

It would be nice to get away from this. One user submitted a patch that avoided this for color schemes by dynamically updating the views instead of the preferences file, but this approach had a couple of issues:

1. It would lazy-load the color scheme on each view as that view was activated, breaking the pretty on the default theme.
2. It would not release the color scheme on the views when the user manually chose a color scheme from the Preferences menu.

The plugin should do the following:

• Store any settings changes in the plugin settings file
• Dynamically update the views to avoid global settings changes
• Update all views at the same time for uniformity instead of lazy-loading the color schemes
• Release changes to the views when the user manually changes the color scheme