Merge perspective.el and persp-mode.el

[conao3]

cc @Bad-ptr

I agree this comment.
#88 (comment)

perspective.el and persp-mode.el provide almost the same feature but there are also different features.

If we can add some options so that users of these two packages don't bother, new persp-mode user don't have to worry about which package to use.
Two package naming have confusing ( tumashu/posframe#29 (comment) ) and MELPA thought is below see top page.

• Up-to-date packages built on our servers from upstream source
• Installable in any Emacs with 'package.el' - no local version-control tools needed
• Curated - no obsolete, renamed, forked or randomly hacked packages
• Comprehensive - more packages than any other archive
• Automatic updates - new commits result in new packages
• Extensible - contribute recipes via github, and we'll build the packages

[gcv]

There's definitely a lot to be said for eliminating the confusion caused by two packages. A good start would be to figure out exactly where the two differ.

[clonex10100]

from what I can tell, the main reason people use persp-mode.el is that perspectives are shared between frames by default. Could we add an option in perspective.el for this?

[gcv]

Certainly possible, but it would take quite a bit of work. Perspective state unfortunately lives in frame parameters, and that has to be undone. To start, I’d have to finally get #91 merged in and thoroughly tested, and I haven’t been able to find time to do it. After that, the actual feature development would have to happen, though that part should be straightforward.

On the subject of “the main reason people use persp-mode.el”, though — isn’t it included by default in popular Emacs distributions, like Spacemacs and Doom?