matrix docs and minor refactoring
misc edits
extra equals overrides and optimisations
equals edits
equality overrides and fixes
more equals overrides
misc refinements
better JoinedVector equals
tests and fixes for matrix shapes
misc improvements
misc edits
add elementProduct for vectors
elementProduct Overrides
add generic dense() coercion for all array types
dense() coercion tests and fixes
dense() overrides and vector construction improvements
more elementProduct Overrides
add isDense() function
extra tests and optimisations
misc AMatrix optimisations