Implemented support for 'initial' in getParameterDefinitions extended to all supported types.

- The varialbe named initial is assigned to the value of paramdef.initial if it's defined,
- otherwise paramdef["default'] is used.
- If both aren't defined, then the variable initial stays undefined.
The initial/default value is applied if the variable is NOT undefined (!== undefined)
Merge pull request #30 from v01pe/initial_for_all_types

Implemented support for 'initial' in getParameterDefinitions extended to...