Config option 'prefer-source' added to schema, refs #553
Support for 'prefer-source' config setting, refs #553
Install/update now uses the new config variable 'prefer-source', fixes #553
Minor code reorg to reduce duplication
Scratch 'prefer-source'; 'preferred-install' is the bee's knees
Merge pull request #1658 from miklosm/iss553

Adds 'prefer-source' option to config
Add more output to the profiled runs, refs #1659
Improved error messages in ArrayLoader

Added package name to exception message when an error occurred in source or dist keys
[docs] Link semantic versioning to semver.org
Merge pull request #1666 from deguif/master

Improved error messages in ArrayLoader
Merge pull request #1668 from igorw/patch-6

[docs] Link semantic versioning to semver.org
Fake a dev lock when a non-dev update is made and there are actually no dev requirements