WIP: Incorporate history from base

[rfourquet]

This is a follow-up of JuliaLang/julia#16357 (comment) (cc @tkelman). I extracted from base the history of primes.jl. I thougth it was not necessary to bother with older history (which was in intfuncs.jl). I also didn't include changes to test/numbers.jl which have tests for primes functions (I don't know how to include only the parts relevant to primes). I see those possibilities (besides doing nothing!):

1. Rebase the history of the package on this branch and make a PR of the result
2. Merge as is (by first deleting base/primes.jl)
3. Someone simply push this branch to the repo, unmerged, as a reference. It would simply be a convenience when hacking on Primes.jl, to avoid having to check the history in the julia repo.

I think I prefer option 3.
For reference, this is how I extracted the history:

function cherry() {
    while read c; do
        git cherry-pick --strategy=recursive -X theirs $c;
        if [ $? != 0 ]; then
            # could add: '! -wholename ./test/numbers.jl '
            find . -path ./.git -prune -o -type f ! -wholename ./base/primes.jl -exec rm {} +
            git add -u
            git commit --no-edit
        else
            find . -path ./.git -prune -o -type f ! -wholename ./base/primes.jl -exec rm {} +
            git add -u
            git commit --amend --no-edit
        fi
    done;
}

function rewriteprimes () {
    git reset --hard a9cbc036ac62dc5ba5200416ca7b40a2f9aa59ea # initial commit
    # last commit listed by 'git rev-list' is the removal of primes.jl
    git rev-list  --reverse master -- base/primes.jl | head -n 33 | cherry
}

What I wanted was to pick the file from base as is and the corresponding commit, I hope cherry-pick resulted in something equivalent.
I had to artificially rebase the result on the initial commit of the package to be able to open a PR here.

[tkelman]

What does it look like if you do git mv base/primes.jl src/Primes.jl ? What would the diff be relative to the current package content? Since the package is already registered we shouldn't modify any existing history, but we can merge new commits into it. We also should have been more careful about acknowledging the license from base. This package is still MIT, but the copyright is held by the contributors to base.

[coveralls]

Coverage remained the same at 96.094% when pulling dcdf586 on rfourquet:base-history into 6467a59 on JuliaMath:master.

[coveralls]

Coverage remained the same at 96.094% when pulling a08d381 on rfourquet:base-history into 6467a59 on JuliaMath:master.

[rfourquet]

After moving it's not directly mergeable, nor is it possible to rebase master onto this branch (option 1 above) without having conflicts to solve (in particular in master the src/Primes.jl file is created almost empty, containing the module declaration and comments). On the other hand, if I then 'git checkout master -- src/Primes.jl' and commit, we get a small diff (essentially docstrings added inline and a couple of small changes), I updated the branch accordingly.
Note that by option 1 I don't mean modifying this package history, but rather to create a parallel one based on master's one, which can then be merged in master.

[coveralls]

Coverage remained the same at 96.094% when pulling a4de93f on rfourquet:base-history into 6467a59 on JuliaMath:master.

[tkelman]

I think we should keep this, just replace "is a part" with "was formerly a part"