4.0.0-alpha

Many Improvements, Many BC Breaks

The Most Significant BC Breaks

• All misspellings of registrable have been corrected (registerable -> registrable) (see #61)
• All magic methods have been replaced with getters.

Other Updates and BC Breaks

• #63: Ensure scheme returns null rather than an empty string
• #64 and #65: Cleans up Exception message