New version compatible with Thunderbird 60.x

[conema]

I think that spymastermatt is a little busy and at the moment he can't accept new PR with fixes.

For that, I created a new version of this theme that is compatible and tested with the new version of Thunderbird (60.x), for the moment. It should be compatible with 50.x

The installation is easier than before, the new theme is an Add-On and it can be downloaded directly from the Thunderbird site with one click.

More information and the download link can be found in:
dark
full dark

[lindhe]

I would suggest making it a real PR even if the maintainer might not have time to merge it. It would make more more semantic sense to me, so we can put improvements and discussion in that thread.

[conema]

The "problem" is that the theme in my repo is not a fork of this one, but a fork of this work, they have almost nothing in common: different license and only a dozen lines of code comes from this repo. In reality, only the design is the same, but the code is practically all different.

An other problem is that, there will exists 3 repository for the 3 different version of the theme (dark/fulldark/light), because for how the addons are built in Thunderbird, I have not the possibility to create only one addon, so only one repo, with all the 3 versions inside, unlike spymastermatt's repo. Thus I find misleading create a PR with "my dark version" -> "spymastermatt's version with dark/fulldark/light".

I opened an issue, and not a PR, because I wanted only to inform users using this theme that I was working at a new version that is being maintained and that is compatible with the last version of Thunderbird.

I hope that I've made my point, I would prefer to continue the discussion of the projects in my repos, but anyway, I haven't any sort of problem to create a PR. If you still advise me to do a PR, I will do so.