Better documentation of :checksum and :checkout properties

* Explain the difference between :checkout and :checksum
* Document that hg method now supports these properties
document 719264d (even though it isn't merged yet)
Document that checksums may not be abbreviated

As requested in #626.
In hg, "checkout" is properly spelled "update"
Added pythonbrew-mini
add recipe for ctxmenu
Flycheck requires the info file to be built again
Update and rename dbgr.rcp to realgud.rcp

The name of the package changed from dbgr to realgud. (It is humbling to have Polish people tell you that your project names are unpronounceable.)
Made a test
Condition in elpa install with refresh package

Added a check for new `package-archives' entries to fetch/update their
archive-contents and regenerate for new configuration of
`package-archives'.
Fixed some mistakes from previous commit.

In particular I neglected the fact that I've introduced a conditional
which blocked package-refresh-contents from el-get-elpa-install in some
cases. Practically the smae bug which I attempted to fix, could have
been encountered if packages were installing in opposite order, whcich i
try to reflect in added variant of the test.
Use a more recent vala-mode than ELPA's
Remove obsolete magithub

See magit issue: https://github.com/milkypostman/melpa/issues/1126
Update dtrt-indent recipe to github; point temporarily at a working fork
Fix a small typo in README.md
Add instructions on replicating a configuration

Use Dimitri's code from #1548

Also add a note to the `init-` packages section about existing
packages.
Ensure el-get's tramp is loaded and not the built-in one
Merge pull request #1567 from dholm/bugfix/tramp

Ensure el-get's tramp is loaded and not the built-in one
Merge pull request #1558 from rocky/patch-1

Update and rename dbgr.rcp to realgud.rcp
Merge pull request #1556 from rrthomas/master

Use a more recent vala-mode than ELPA's; remove magithub; fix dtrt-indent; add instructions for replicating a configuration