Migrate records in mix to maps.
Fixed typo and improper use of their in documentation
Merge pull request #2230 from mgwidmann/master

Fixed typo and improper use of their in documentation
Merge pull request #2229 from MSch/mix-maps

Migrate records in mix to maps.
Add spaces in between |
Test git in dep folder to consider checked out

If the .git folder of a dep becomes corrupted, any git command
issued by mix could find a parent .git folder and wipe the parent
tree.

This fix only consider a git dependency checked out if git is able
to read the .git folder.

Signed-off-by: José Valim <jose.valim@plataformatec.com.br>
Consider only valid .git repos as checked out
Do not recompile the whole project when an .eex file changes

Right now, we simply trust the user that any external
dependency will be listed as a @file and use those
to track any external dependency.