Add typealiases. Codestyle improvements.

[hluhovskyi]

Hello! Thanks a lot for your library.

The purpose of this PR is to clean up some parts of codebase according to Coding Conventions Also, this PR's brings typealiases for all selectors and some other cases which significantly improve readability.

Here is a short list of general changes:

• Change builder methods to use apply() which allows to omit return this
• Replace all lambdas of selectors with its typealiases, e.g. FlashSelector, QualitySelector
• Specify return type explicitly for methods which are exposed. This change allows to not break compatibility of open interface in case of any kind of refactoring.
• Make some methods to use expression body instead of block one
• Small changes (use range operator, sort modifiers, convert lamda to reference)

If some changes don't fit your needs feel free to comment what should be changed or reverted.

[hluhovskyi]

Thanks for merging PR! Regarding your comments I've just tried to follow conventions mentioned above. And in the end such small things can vary from developer to developer. So in case if something related to this PR should be changed let me know I will try to help with it.