document DateType limitations
breaking lines to <80 characters
moved note into separate include. removed blockquote from PHP manual
Improve serialization example

Improve serialization example

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | yes
| Applies to    | all
| Fixed tickets | #2225
Merge pull request #2403 from joelclermont/issue_2266

document DateType limitations
setValues() instead of setValue()
change description text to better describe the modfied examples
[#2420] Simplifying english
new cookbook article on using empty data for form classes
Document verbosity levels
[#2408] Minor tweaks for OutputInterface verbosity level discussion
Merge pull request #2415 from joelclermont/issue_998

new cookbook article on using empty data for form classes
[#2415] Proofreading great new empty_data document and expanding some of the examples
Merge branch '2.0' into 2.1

Conflicts:
	cookbook/form/index.rst
	cookbook/map.rst.inc
	reference/forms/types/options/date_widget.rst.inc
[#2415] Updating empty_data document for 2.1 changes