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"
Add test code for dimitri#1615
Merge pull request #1633 from npostavs/menu-fontify

fontify package-list menu correctly
Fix the way that el-get accesses `url-proxy-services`.

el-get gets the proxy from `url-proxy-services` by

    (cadr (assoc "http" url-proxy-services))

However, `url-proxy-services` is an alist which looks like

    '(("http" . "hostname:portnumber') ...)

So using `cadr` is wrong.  Replace it with `cdr`.

This commit closes dimitri#1615
Merge pull request #1632 from dochang/issue-1615

Fix the way that el-get accesses `url-proxy-services`
work around tramp loaddefs bug

tramp-loaddefs.el uses `tramp-verion' before it's defined, work around
this by loading trampver.el first.
tramp.rcp: little cleanup

remove :module from CVS times, and needless nesting in :build.
Merge pull request #1634 from npostavs/tramp-fixup

work around tramp bug
Merge pull request #649 from DarwinAwardWinner/doc-improvements

Doc improvements
replace flet with let+lambda+funcall

flet is marked obsolete in 24.3 resulting in quite a lot of annoying
messages. The intended replacement is cl-flet, but that is unavailable
in earlier emacsen, so we can't use that either.
Merge pull request #1638 from npostavs/no-flet

replace flet with let+lambda+funcall
Fix el-get-elpa-update-available-p for Emacs >24.3
Call package-initialize in el-get-elpa-update

Otherwise, `package-alist` is nil when `el-get-elpa-update-available-p`
is called, which yield another "Wrong type argument: arrayp, nil" error.
Comment why checking available-package
benchmark-init recipe
Merge pull request #1640 from dholm/recipe/benchmark-init

benchmark-init recipe
Merge pull request #1639 from tkf/fix-el-get-elpa-update-available-p

Fix el-get-elpa-update-available-p for Emacs > 24.3