Minor updates to README for improved clarity
Add shape and size properties to MetadataTable

Necessary for stats fun!
Add unique discrepancy occurrence stats
MetadataTable.field_values now computes raw counts
Add total counts for each discrepancy type
Add invalid count for cells that don't match vocab
Add comma and brackets rules
Add numeric column detection

Numeric columns are ignored in report for now
Merge pull request #11 from jrrideout/issue-8-again

Basic stats