Started adding some tests for the TwoPoint object.
Fixed bad variable reference in available mesons and made static method
Added override for save_raw function to prevent misuse
Fixed several bugs in TwoPoint.add_correlator projection code
Added empty test for meson correlator - to be completed
Added function to to obtain a given jackknife datum.
Added a couple of items to the todo list
Added two helper static functions to parse and create correlator names

Added regex package as that's essential for correlator names etc.
Added correlator projection function to save code repetition.
Added function to generate random variable names for tests.
Generalized compute_correlator function to accept any two interpolators and propagators.
Redesigned twopoint init function so that TwoPoint is less propagator dependent.
Updated save and load functions to reflect new TwoPoint design.
Renamed available_mesons to something more general
Added get_correlator function and refactored add_correlator to use new functions.
Added test for get_correlator
Rewrote test for add_correlator to reflect new TwoPoint design.
Rewrote meson_correlator function to not rely on built-in propagators
Added test for TwoPoint.meson_correlator.
Renamed meson correlator function to make more verbose.