first, remove confusing default column
add version section to table of contents
lay out version requirements
update immutability language with version
fix number of authority
revise per comments
Merge branch 'master' of https://github.com/adlnet/xAPI-Spec
Merge branch 'master' into versiondetails
tweak wording
add format req to table, also tidy up a few typos such as spaces in the version header name
Merge pull request #196 from fugu13/versiondetails

Attempt to specify the behavior of the version attribute for statements