Implemented plugin manager

[astrofrog]

A simple GUI will follow (in this PR). Plugins are enabled unless explicitly disabled.

[astrofrog]

This now implements a GUI manager for plugins:

Users need to restart Glue for changes to take effect, but otherwise it works as expected.

(oops just realized window title is wrong, fixing)

[astrofrog]

@ChrisBeaumont - this is ready for review if you are interested

[ChrisBeaumont]

Looks good to me!

On Sunday, July 5, 2015, Thomas Robitaille notifications@github.com wrote:

@ChrisBeaumont https://github.com/ChrisBeaumont - this is ready for
review if you are interested

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Reply to this email directly or view it on GitHub
#682 (comment).

[astrofrog]

I think I'll need to add some tests for this, will do this week.

[astrofrog]

This now includes unit tests, and also implements a way to override the config dir during tests (in fact, it's overridden by default by a temp directory and can be further overridden by individual tests)

[astrofrog]

Ok, this is ready for a proper review.

One open question is how to deal with plugins and session files. If I use a plugin and save a session which contains a reference to that plugin, then load the session up, should it load the required plugins even if the required plugins were disabled before? Should it give an error? What about plugins that aren't even installed?

[astrofrog]

@ChrisBeaumont - would you like to review this before I merge? Do you have any thoughts about the question of saving sessions that use plugins?

[ChrisBeaumont]

This looks good to me. Can we attempt to load saved plugins, with graceful
fallback if they aren't available?

On Saturday, July 18, 2015, Thomas Robitaille notifications@github.com
wrote:

@ChrisBeaumont https://github.com/ChrisBeaumont - would you like to
review this before I merge? Do you have any thoughts about the question of
saving sessions that use plugins?

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Reply to this email directly or view it on GitHub
#682 (comment).

[astrofrog]

For the loading of plugins when restoring sessions, I've opened this issue: #721 (since this is an issue that is independent on this PR)