Idea from Marius.  This seems to improve exception performance quite a bit,
though interestingly also some of the other benchmarks as well.

like we had to do for getattrGeneric and setattrGeneric

I guess all the other slots will eventually follow as well.

And change for loops to instead of calling __hasnext__ directly, to
call objmodel::hasnext() which calls tpp_hasnext.

tiny misc improvements

Things are getting pretty messy, but it's an incremental step towards doing things more
like CPython which should ultimately make things simpler.

The use of the tp_getattro slots (even though they're the CAPI slots) seems to lead to
about a ~7% improvement in interpreter-only speed.

ie if we set __getattribute__ on a superclass, we have to update
tp_getattro on all subclasses.  We've always been broken on this, but
this didn't really matter as much until now since we would internally
check __getattribute__ and not tp_getattro.

tp_subclasses is a list of weakrefs, which means that we need weakref
support before we can start finalizing classes.  which means we have to
add a whole slew of things into the bootstrapping section.

We should probably just do this in a more systematic way, but I'm
not sure what that would be...

This is the analogue of 9f63b62e but for getattr instead of setattr:
previously there was no way to run the default getattr logic, since
getattrInternalGeneral would always check for a custom __getattr__
or __getattribute__.  This meant that object.__getattribute__ was
the same thing as getattr() and that PyObject_GenericGetAttr was the
same as PyObject_GetAttr, which were not correct.

update INSTALLING.md, and libsqlite-dev in cmake section

Add support for unicode literals when using pypa

split the getattr/setattr of softspace into two try blocks

For calling runtime functions, we usually just have one function that
handles all types.  We can bypass most of the resolution work by just
skipping to that function.

cpython can be observed setting softspace on an object even if it doesn't start with it.
the getattrInternal in softspace() throws an exception the first time through since the
attribute isn't present.  if we don't turn around and set it on the object, we throw
every time we print, which causes a pretty large perf regression (from ~6 seconds to ~17 seconds.)

Previously we would keep its elements alive but not the actual array itself?
I think this is what was crashing fasta.py, which is now working with
this change.

I couldn't reproduce the presumed bug in a smaller testcase though.

Mangle functiondef and classdef names in the type analysis

Marius beat me to the punch with the fix this time :)

Fix a threading.local() and a unicode type analysis bug and add support for round(f, 0)

The GC did not visit the thread state dict, which made it forget it's entries after a gc collection