Feature/integration fixes

This branch will address issues #212 (closed) and #208 (closed).

The most significant changes are as follows:

• Implement the coordinate system described by Kabsch 1988 used in XDS
• Implement a shape library which stores a cache of 1d & 3d peak profiles as well as 3d inertia tensors
• Rewrite peak integration so that the integration mode may be chosen at runtime
• Implement new integration modes
• Gaussian fit
• 3d profile fit
• 1d profile fit
• I/sigma optimization
• Fix various bugs and remove dead code along the way