Add -to-head and -shuffle

[cireu]

Close #283 and #285

The tests won't pass in Emacs 24.2 or any lower version because we use random to create random seed. And this feature was introduced in Emacs 24.3. But I think the function of -shuffle can work well.

[debanjum]

@cireu, any blockers on this (apart from the merge conflicts)? Anything I could help out with?
It'd be great to have -shuffle in dash.el!

[Fuco1]

For the tests we can use cl-flet

(cl-flet ((random (n) 1)) (random 5))

I don't remember if this existed in Emacs 24.1 and .2 though.

[basil-conto]

Yet another possibility, as an alternative to controlling the randomness, is to enumerate all possible shuffle results.

[Fuco1]

is to enumerate all possible shuffle results.

I don't think that would be possible. Factorial grows faaaaast.

[basil-conto]

is to enumerate all possible shuffle results.

I don't think that would be possible. Factorial grows faaaaast.

I meant for small test cases of course :)

[Fuco1]

Uh, what happened here?:O The diff is thousands of lines

[cireu]

damn this PR was so long ago I still use the master branch of fork to create PR, so silly 😅 .

I will create a new PR for this.