[WIP] QBMX

Things in here that are done:

• QBMX FMM

Things not in here that need to be put in:

• convergence tests for QBMX

Things not in here that I currently plan for future merge requests:

• QBMX-friendly refinement
• some sort of target side association (currently the side always needs to be specified for a set of targets)
• direct eval