harmless oversights

clean up dead function, copy pseudo-boundary condition
remove harmful "shrinking" flag, other cleanups

The lattice once had infinite grow/shrink cycles, but to break that we
only need to quit after a growth which followed a shrink... not vice
versa. As is, it would just spin forever if it needed to grow but had
shrunk.
Massive interpolation speedup, fixed phi0 feedback

Pchip is darn slow, was taking 75% of the time inside SCFprofile. The
previous method of converting phi0 into lattice space was deeply flawed.
This way may not be perfect but it is at least sometimes accepted by the
check inside SCFsolve.
Add c extension for inner loop

It crashed when I added the code into reflmodule directly, but this
works and doesn't seem too invasive. The only downside is there are two
pyd files...