getters setters and other enhancement to typescript definitions

[parro-it]

• I add tslint package to lint typescript defs file.
• Changed syntax for nested enums from static property to namespace to fix TS error.
• Manually add getter setters (as @mischnic said, mapped properties cannot be used for this)

While doing these changes, I also find some error in type of properties that I'm going to fix with further commits here.

[mischnic]

Unfortunately, clang-format doesn't really work well with typescript