Moving all FCL and BCL documentation into its own section and making it awesome

[cartermp]

Currently the primer has a link to a document that isn't in the TOC tree describing briefly what the FCL is, giving a brief overview of the BCL and some examples of what the BCL and FCL contain.

There is also a section called "Base Class Library", which I think is a good candidate for renaming to "Framework Class Library" and modifying it to contain all things FCL, including a link to reference documentation. This would include:

• Overview of the FCL with a diagram showing its relationship with .NET Managed Langs
  • Section with BCL overview and example of its contents, with link to reference docs
  • Section with other FCL examples, with links to reference docs
• Article about FCL libraries which are important for cloud devs
  • Snippet about each relevant library for cloud devs with sample code highlighting a common use case in C#, VB, and F#
  • Link to reference docs for each library
  • Links to sample applications or full code samples
• Article about FCL libraries which are important for mobile devs
  • same as for the cloud devs article
  • Links to the UWP samples and other platform samples

I see value in making it clear to developers the relationship between the libraries and the languages and providing conceptual docs + code samples covering some common scenarios. This is a large enough area that it also demands its own section.

[cartermp]

Closing for now; we have more stuff to hash out before we can consider writing this documentation.