Fixed typos in Mix.Deps.Retriever docs
MAKE: allow more verbose build output

people can now run:
  make Q=
to get a the maximum of build output
MAKE: standardize install variables

- convert to autotools-like variables commonly used in build scripts
- respect DESTDIR (used for temporary install locations)
- fix symlink logic to work with DESTDIR
${foo##bar} is posix, see:
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html
under "2.6.2 Parameter Expansion"
- quote all variables that can contain whitespace
(make does not take care of that!)
MAKE: respect LIBDIR variable

Some distributions do not use plain "lib", rather "lib64"
and "lib32". Allow to control this variable.
Merge pull request #1407 from gentoo/Makefile

Makefile improvements
Delete files in the manifest instead of removing the loadpath
Merge pull request #1408 from meh/mix-leex-yecc

Delete files in the manifest instead of removing the loadpath
Ensure eval callbacks gets a fresh vars dict
Simplify manifest API and put tests back on green
Clean up mix tests
Optimize stale handling
Start app before perfoming requires
Fixed doc typos in OptionParser
Merge pull request #1412 from jwarwick/optionparser_docs

Fixed doc typos in OptionParser
Fixed doc typos in Mix.Tasks.Test
Merge pull request #1415 from jwarwick/mix_help_typos

Fixed doc typos in Mix.Tasks.Test
Implemented Record.__record__(:index) syntax, Issue 1414.
Updated docs to use __record__(:index) instead of __index__
Updated System and Mix to use __record__(:index) syntax
kwlist are inspected as a list of tuples with raw: true