Lots of smaller fixes (#185)
Lots of smaller fixes (#185)

* remove statement references leftovers. Fixes #171

* some work on JSONPath. Might be sufficient for #170.

* clear up language around contextActivities normalization. Fixes #169

* clarify activity definition requirements. Fixes #161.

* clarify use of contentType. Fixes #160.

* move document resource id requirement. Fixes #157

* reorder relationship properties. Fixes #151

* specify arrays. Fixes #148

* add wasRevisionOf clarification. Fixes #146.

* move profile versions description. Fixes #145

* add short note on seeAlso-definition interaction. Fixes ##144

* add introductory section for Profile Properties. Fixes #141

* reword compact URI requirement. Fixes #138

* remove inadvertent use of documents. Fixes #137

* rearrange wording of compaction requirement. Enough for #134?

* remove definitional ambiguity of patterns. Fixes #129

* change rule to presence. Fixes #126

* remove core concepts. Fixes #123

* hyphenate up-to-date

adlnet/xapi-profiles,fugu13/xapi-profiles