Export Numerical object and move KAPPA constant there.
Commit initial support for Shape class.

Hit testing is still missing.
Correct Numerical.KAPPA value.
Use Item#type instead of instanceof checks for better performance.
Large refactoring of Style handling for notable speed improvements.
Restructure code organization by separating canvas related utility classes into separate canvas folder, and move inclusion of utilities classes to beginning.

Was needed because Numerical.KAPPA is accessed at compile time.
Use Color object for default.
Document new approach to styles.
Simplify Style creation.