Add additional volume_state and volume_item attributes.

The following attributes were added:
FILE_SEQUENTIAL_WRITE_ONCE

FILE_SUPPORTS_EXTENDED_ATTRIBUTES

FILE_SUPPORTS_HARD_LINKS

FILE_SUPPORTS_OPEN_BY_FILE_ID

FILE_SUPPORTS_TRANSACTIONS

FILE_SUPPORTS_USN_JOURNAL

Issue #164

	modified:   schemas/windows-definitions-schema.xsd
	modified:   schemas/windows-system-characteristics-schema.xsd
Edit type in documentation.

Issue #164
	modified:   schemas/windows-definitions-schema.xsd
	modified:   schemas/windows-system-characteristics-schema.xsd
changed documentation for nillable entities

changed documentation to for multiple nillable entities to read 'not
collected' instead of 'does not exist'.
spelling error

changed inclueded to included.
Merge pull request #169 from ccoffin/issue55

fixes #55
Merge pull request #167 from LuisNunez/issue164

Update volume_state and volume_item attributes #164.
Modifications to address issue #41

Documentation for xpath changed to text proposed/agreed on the dev list.
Add clarification for time_difference function in both schema and language spec. closes #44, closes #47
Merge pull request #185 from ccoffin/issues44_47

Add clarification for time_difference function in both schema and langua...
Merge pull request #182 from mcokus/issue41

Modifications to address issue #41
Including System Metric elements

Added documentation for systemmetric_item, fixed system_metric_state
typo. Fixes #14
Updating EntityItemSystemMetricIndexType documentation

Variable references and pattern matches do not appear in Items as
indicated.
Merge pull request #195 from drothenberg/systemmetric

Including System Metric Test. Closes #14.
moving annotation documentation so it will get picked up by the xsl that generates the html documentation.
Merge remote-tracking branch 'origin/master' into cmaster