Filter out and translate invalid sockopt names.

-Implement GetSockOpt / SetSockOpt
-Fix bug in RecvFrom where sending from localhost
 does not fill in src_addr/src_addr_len on Linux

Closes #1277

Involves making asserts use printf instead of the log functions (log functions are asynchronous and, as such, the log won't be printed in time)
As such, the log type argument was removed (printf obviously can't use it, and it's made obsolete by the file and line printing)

Also removed some GEKKO cruft.

Stubbed CreateMemoryBlock

Using Berkeley sockets, and Winsock2.2 on Windows.
So far ftpony creates the socket and accepts incoming connections

SOC_U: Renamed functions to maintain consistency

Also prevents possible scope errors / conflicts with the actual Berkeley socket functions

SOCU: Close all the opened sockets when cleaning up SOCU