add envisage

[grlee77]

Add envisage as required by #285.

This PR will require #391, #394 and #395 to be merged first

[conda-forge-admin]

Hi! This is the friendly conda-forge-admin automated user.

I just wanted to let you know that I linted all conda-recipes in your PR (recipes/envisage) and found it was in an excellent condition.

[grlee77]

I listed the license here as BSD 3-clause, but upon further inspection there are a handful of icon images that are under a variety of other licenses. See the details in this file:
https://github.com/enthought/envisage/blob/38c1ffc40cdd0b9a2e19faed80c8f253a08c553c/image_LICENSE.txt

[jakirkham]

Could you please cherry-pick this commit ( aa7a93b ) that will fix the Windows build failure?

[jakirkham]

Once the cherry-pick is done and CI passes, am more than happy to merge this.

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipes/envisage) and found it was in an excellent condition.

[grlee77]

looks like this is now good to go

[jakirkham]

Thanks @grlee77.