Basic reorganization of development file structure.

Middleman is suited for generating either

(1) Small sites, or
(2) Small parts of small sites.

Because my site will have different content for /journal/,
/essays/, etc, I had to take on a more complex development
process.

Each of the major content-holding directories (journal, essays,
news, each blog directory) will have their own branch. Each
branch:

(1) Will be named for its directory, except for the blogs
    (eg, branch news will develop /news/ under _news)
    (A). Each blog will be developed under its own directory
         (eg, branch Amperset will develop hypothetical blog
         'Amperset' under _amperset)
(2) Will rsync any shared data (like data/*yml files and
    partials) with the main source directory (under branch
    devel)
(3) Will build and rsync all data with pre-written scripts,
    not 'middleman build' and 'middleman server'.

Any site-wide content like /authors/ or /about will be kept under
the devel source directory.

Development will then go like this:

(1) A major content-holding directory, say /journal/, will be developed.
    (A) Changes will be made.
    (B) Changes will be committed.
    (C) Changes will be built with ./build.sh.
    (D) Changes will be tested with ./server.sh.
    (E) When all errors are worked out, changes will be built again
        with ./build.sh
        (a) It is important that ./build.sh is the final script run
            before a commit, so no extra files are sent to the
            'devel' build directory.
    (E) Changes will be commited and pushed to branch 'journal'.
(B) In branch devel, the ./build script will be run, which will do
    the following:
    (1) rm -rfv build/* deploy/*
    (2) mkdir -p build/<content-holding directories>
    (3) cp -Rv _<content-holding directory>/build/* build/<content-holding
        directory>/
    (4) middleman build
    (5) cp -Rv ./build/* ./deploy/
(C) In branch devel, middleman --server will be run, and the entire site
    will be tested; any mistakes need to be fixed and scripts run again.
(D) Changes committed in branch devel and deployed.
(E) Descend into ./deploy, 'git add .', 'git commit -a -m ""', 'git push
    origin master'
Gitignored independently developed dirs
Added _essays directory