[#2366] Fixed link
remove the pattern option in DateType
Documenting the virtual option for types where it makes sense.
Fixing some syntax issues
Fixed declared type of property 'traverse'.
Merge pull request #2367 from WouterJ/issue_2366

[#2366] Fixed link
Missing interface in code example
Added missing use statement
Change confusing part in ex. of class validator

Change confusing part in examples of class custom validator in YML and XML.
POST JSON data
[#2396] Comment tweak on submitting raw request body
Merge pull request #2400 from xabbuh/fix-pattern-option-in-datetype-docs

remove the pattern option in DateType
[#2400] Removing reference to removed include
Merge pull request #2401 from Sgoettschkes/issue1387_2.0

Documenting the virtual option for types where it makes sense.
[#2401] Fixing a typo thanks to @michaelperrin and adding a reference link
Removing removed referene
Merge branch '2.0' into 2.1

Conflicts:
	reference/forms/types/birthday.rst
	reference/forms/types/date.rst
	reference/forms/types/datetime.rst
	reference/forms/types/time.rst