Merge pull request #2 from adlnet/master

updating
Merge pull request #3 from adlnet/master

merge adl master
quick fix to objectType in voided section
Update xAPI.md

grammar and wording clarifications in section 2
Update xAPI.md

grammar and wording improvements in section 1
Update xAPI.md

grammar and wording in section 3
Update xAPI.md

grammar and wording in section 4.0 and 4.1 intro.
replace query api reference with statement api. Fixes #143
modify context activities, including description tweaks and array values. Fixes #28. Related to #75, which might be okay to close.
shorten long line lengths
Update auth options to match prior table
Moved inverse functional identifiers into their own sub-section

This change started as an attempt to clarify that actors do NOT require inverse functional identifiers, rather they require a valid agent or group -- which in turn require inverse functional identifiers except for anonymous groups. In order to help clarify that I gave inverse functional identifiers their own sub-section, since talking about IFI's being required in the actor section makes it sound like they're required for all actors.
Merge pull request #140 from creighton/voidedtypo

Voided objectType was Statement not StatementRef
Merge pull request #144 from fugu13/removequeryapi

Replace query api reference
Merge pull request #146 from michaelwheeler/patch-1

Update auth options to match prior table
minor changes based on feedback

* fixed a typo
* re-worded definition of Inverse Functional Identifier
Merge pull request #147 from bscSCORM/actor

Moved inverse functional identifiers into their own sub-section
rephrase singleton to single
Fixed small typo pointed out by @bscSCORM
Merge pull request #145 from fugu13/arraycontextactivities

Changes to contextActivities as discussed in #28