Drops Thumb2 arch size by 24 bytes.

Stream methods were added to normal sockets as in the unix port.

WLAN needs time info when validating certificates.

The TimeoutError is useful for some modules, specially the the
socket module. TimeoutError can then be alised to socket.timeout
and then Python code can differentiate between socket.error and
socket.timeout.

When "micropython -m pkg.mod" command was used, relative imports in pkg.mod
didn't work, because pkg.mod.__name__ was set to __main__, and the fact that
it's a package submodule was missed. This is an original workaround to this
issue. TODO: investigate and compare how CPython deals with this issue.

When enabled this allows the internal storage to be split over 2
contiguous regions of flash (two segments), and so the storage can be
increased.

This option is disabled by default, giving original behaviour.

CPython raises SystemError in this case, but we don't have that enabled, so
raise ImportError.

Doesn't allocate memory and returns original string if no replacements are
to be made.

Previous to this patch each time a bytes object was referenced a new
instance (with the same data) was created.  With this patch a single
bytes object is created in the compiler and is loaded directly at execute
time as a true constant (similar to loading bignum and float objects).
This saves on allocating RAM and means that bytes objects can now be
used when the memory manager is locked (eg in interrupts).

The MP_BC_LOAD_CONST_BYTES bytecode was removed as part of this.

Generated bytecode is slightly larger due to storing a pointer to the
bytes object instead of the qstr identifier.

Code size is reduced by about 60 bytes on Thumb2 architectures.

Recognize and handle "package not found" error.