Fix bad conditional logic when checking for +iex
Merge pull request #2175 from bitwalker/windows-shell-fixes

Fix bad conditional logic when checking for +iex
Small grammar fix
Minor grammar tweak

Subject/verb agreement at the top
Merge pull request #2178 from augiedb/patch-2

Minor grammar tweak
Merge pull request #2177 from augiedb/patch-1

Small grammar fix
Proper error message for bad args to 'mix help'

Closes #2179.
Update example to use Map.put/3, accordingly with the last proposal

[Proposal 1](https://gist.github.com/josevalim/9acd0fe43063cbc33aa6)
has the update operation also put new keys in the map, while the
[2nd proposal](https://gist.github.com/josevalim/b30c881df36801611d13)
doesn't support this. The docs reflected the first proposal.
Merge pull request #2180 from MSch/docfix-special_forms-map

Docfix: Use Map.put/3 in Kernel.SpecialForms struct docs.
Spruce up the output format of ex_unit

Conflicts:
	lib/ex_unit/lib/ex_unit/assertions.ex
Clean up new formatter implementation
Reject __struct__ field on struct/2
Properly format and indent test output
Allow overriding of undefined dependency SCM

This allows a developer to override an unrecognized SCM without Mix
raising.
Merge pull request #2181 from ericmj/override-undef-scm

Allow overriding of undefined dependency SCM
Improve noscm error message
Release v0.13.0
Start v0.13.1-dev