Recognize parameter when there is no description on its signature and remaining description is not a new node
Only Paragraph and Code nodes are considered for asset bodies
Do not complain about indentation if it is a symbol reference
Allow multiple metadata nodes in a blueprint
Will be a normal asset if model reference indentation is 8 spaces
Return 'undefined symbol' error when symbol not found
Give warning when no headers specified in headers section
Don't warn about API name by default
Cleaned up logic for symbol reference parsing
Merge pull request #155 from apiaryio/pksunkara/refactor

Regression fixes
MSON AST origin. MSON property parser origin.

Conflicts:
	snowcrash.xcodeproj/project.pbxproj
Implicit use of Value<T>::value_type in element value helper
Rename ValueType to DataType for better clarity
Signature parser origin, MSON element parser origin.

Conflicts:
	snowcrash.gyp
	snowcrash.xcodeproj/project.pbxproj
Add checking & warnings to the signature parser

In addition the signature parser is now of standard-parser grade consuming
node iterators and parser data. Also the signature parser now returns any
remaining multiline content.
Support for `-escaped signature variables
Fix project files
SectionTraits origin, singleton sections check origin
MSON element signature parsing completed
Fix wrong copy-pasted test, remove unimplemented property parser tests