0.6.1 - Minor Improvements

• the application root directory is always included in the header search path (enables various uses of the config system to select user-defined headers to include)
• add a newline at the end of JSON files when writing them (since most editors will add this when these files are manually edited)
• clarify documentation for using hg repos (thanks @jagomo!)
• fix an error when updating a non-existent target