Add support for Solidity-like libraries

[xermicus]

As documented here.

There are a number of things to consider, notably:

• "if library functions are called, their code is executed in the context of the calling contract"
• "libraries are assumed to be stateless." and " if a library’s code is executed using a CALL instead of a DELEGATECALL or CALLCODE, it will revert unless a view or pure"
• "In particular, it is not possible to destroy a library."
• linking

[SkymanOne]

What's the status of this? Are you going to tackle it anytime soon? if not, can I take over the issue?