Moved assignment compatibility to its own small section. Although most rules are type-specific,
some are not and it reduces redundancy to combine them.
Also, more experimentally, wrote a section on comparison compatibility.
R=gri
DELTA=382 (125 added, 122 deleted, 135 changed)
OCL=25355
CL=25382
No textual changes except for html formatting.
Seems like a fine intermediate step.
R=r
DELTA=7638 (4079 added, 3559 deleted, 0 changed)
OCL=25211
CL=25224