Refactoring and general project improvements

[doroxz-zz]

This huge update contains:

• Refactoring and general code improvements (Closes Refactoring & Documentation #35 )
• Created script for data types generation according to schemas (Closes Match data types with new schemas #36 )
• Improved caching mechanism for requests (Closes Add request caching mechanism #13 )
• Result types are reworked; now result type contains request property with information from which registry and repository this data fetched (Closes Return custom repository with dependency #15 )
• Also result type defines error property (Closes Unification a errors for all package managers #23 )
• Execution errors have been classified; All exceptions and promise rejections were handled.
• Nuget registry api was added (Closes Add support for nuget #20 )
• Integration with gitbook; Online docs have exported classes and types description, basic community guidelines (Closes Create documentation #32 )

[xferra]

@doroxz I’d like to split this PR, please try to follow the rule ‘1 Issue = 1 PR = 1 Commit’ as much as possible.

[doroxz-zz]

@doroxz I’d like to split this PR, please try to follow the rule ‘1 Issue = 1 PR = 1 Commit’ as much as possible.

Well..

[xferra]

@doroxz Of course it’s possible to have several commits on 1 pr, but then it should belong to 1 feature.