v2.12.0: Auto merge of #660 - kbknapp:issue-588, r=kbknapp

v2.12.0 (2016-09-13)

Features

• Help: adds ability to hide the possible values on a per argument basis (9151ef73, closes #640)
• help: allow for limiting detected terminal width (a43e28af, closes #653)

Documentation

• Help Wrapping: removes the verbage about using '{n}' to insert newlines in help text (c5a2b352)
• Value Delimiters: updates the docs for the Arg::multiple method WRT value delimiters and default settings (f9d17a06)
• appsettings: Document AppSetting::DisableVersion (94501965, closes #589)

Bug Fixes

• AllowLeadingHyphen: fixes a bug where valid args aren't recognized with this setting (a9699e4d, closes #588)

Improvements

• Help Wrapping:
  • clap now ignores hard newlines in help messages and properly re-aligns text, but still wraps if the term width is too small (c7678523, closes #617)
  • makes some minor changes to when next line help is automatically used (01cae799)
• Value Delimiters: changes the default value delimiter rules (f9e69254, closes #655)
• YAML: supports setting Arg::require_delimiter from YAML (b9b55a39)

Performance

• help: fix redundant contains() checks (a8afed74)