add test/vis example
add table metadata to each col, row and cell in layout data

note: so cell and row-label cell widths can be proportioned to number of cols
change summary to return hash of calculations (more structured)
refactor matrix into separate object

add matrix.fetch* methods

add matrix indexing for accessing values by order vs key

add matrix.fetchIndexOffset()  (not tested)
fix matrix indexPaths, offsetPath

refactor matrix data-verification tests

add matrix fetchOffset, fetchIndexOffset tests

note offset fetching is slow, need to try something else
note re different matrix data structure
reimpl matrix as flat array with sha1-based hash indexes
version bump