Rename getStatus() and getStatusDuration() methods to getState() and getStateDuration(), respectively

[aguecida]

Issue #, if available:

#37

Description of changes:

• Renamed getStatus() and getStatusDuration() methods to getState() and getStateDuration(), respectively, so that it matches the methods as shown in the documentation (for both the Contact and Connection classes).
• The methods can still be called using the old naming convention for backwards compatibility. This is equivalent to how agent.getStatus() and agent.getState() reference the same method.
• Use the ContactStateType enum internally, as opposed to ContactStatusType
• Updated the type definition file to match the new method names.

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[h3adache]

Thanks for the contribution @aguecida
The documentation was updated to reference both so I'm going to close this request.