ref: use basic code from FCS point correlator

[paulmueller]

dwaithe/FCS_point_correlator#4

[paulmueller]

It has been a very long time for me.

@tsbischof Did #213 make this issue obsolete?

[tsbischof]

Mostly. I rewrote the correlator in numpy to replace the fib4.pyx here, and added ptufile to enable ptu files. The remaining gap would be to bring in support for pt2/ht2/ht3 files if anyone still uses those.

[paulmueller]

OK, thanks. Since I don't see any explicit requests for pt2/ht2/ht3, I am closing this one.