Clean up Imports, Capitalize Enum members, Refactor

[NZSmartie]

This is mostly a cleanup of the library to make using the library more obvious for developers.

• [x] In example.py there are too many imports... try to restrict it to

  import hidparser

• [x] Consider renaming the library import to hid since parser implies it's used for parsing, and not creating or using descriptors. Not going to happen as pyhidapi uses this namespace already and I do not want a name conflict
• [x] Enum members should be capitalized. Although python libraries itself son't follow this rule, in PEP 8 Constants it recommends all-caps with underscores.

[NZSmartie]

From 6888558ec273e09f297039f8737b1603a2bfdbb8

For code style consistency, clases that inhert Enum now ahve capitialised members as they represent constant values. However, when they are used for creating members in Collections, they are converted to lowercase for code readability and consistency