[Templating] Add documentation about generating versioned URLs
[Book][Security] constants are defined in the SecurityContextInterface
[Expression Langage] be consistent in "print/print out" uses
[#3729] Making minor changes thansk to @WouterJ and @xabbuh.
[#3729] Removing 3rd argument to isWritable - this doesn't exist in the final merged item
[Book][Validation] configuration examples for the GroupSequenceProvider
Add missing autocomplete argument in askAndValidate method
Added some exceptions to the method order in CS
Fixed broken link in "Handling Authentication Failure"
Fixed typo
Fixed broken link.
fix field count.
feature #3803 [Book][Validation] configuration examples for the GroupSequenceProvider (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
----------

[Book][Validation] configuration examples for the GroupSequenceProvider

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets |

This pull requests adds examples in different formats for the GroupSequenceProvider feature of the Validator component (it's the completion of #3369).

Commits
-------

bfd2af4 [Book][Validation] configuration examples for the GroupSequenceProvider
bug #3805 Add missing autocomplete argument in askAndValidate method (ifdattic)

This PR was merged into the 2.3 branch.

Discussion
----------

Add missing autocomplete argument in askAndValidate method

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.3
| Fixed tickets |

Commits
-------

d8059e2 Add missing autocomplete argument in askAndValidate method
minor #3807 Added some exceptions to the method order in CS (stof)

This PR was merged into the 2.3 branch.

Discussion
----------

Added some exceptions to the method order in CS

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets | n/a

See https://github.com/silexphp/Silex/pull/936#issuecomment-40591230 for the reason. Formalizing this case in the doc is a good idea IMO.

Commits
-------

3b8e644 Added some exceptions to the method order in CS
[#3807] Fixing period to semicolon thanks to @xabbuh
minor #3784 [Expression Langage] be consistent in "print/print out" uses (mickaelandrieu)

This PR was merged into the 2.4 branch.

Discussion
----------

[Expression Langage] be consistent in "print/print out" uses

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?  | no
| Applies to?    | 2.4, 2.5
| Fixed tickets? | no

Commits
-------

c0fdca7 [Expression Langage] be consistent in "print/print out" uses
Merge branch '2.3' into 2.4
Merge branch '2.4'
[Form] Added documentation for Form Events

Added initial documentation for Form Events:

* List of events
* Use cases for each event
* Description of the events workflow
* Flow charts for illustration

Updated PR with comments from @WouterJ and @MyKiwi

Took into account @cordoval's feedback

Additional improvements

* Added more examples from the Form component's code
* Moved the cookbook's 'register a subscriber using a callable' section into the form events documentation

Took into account @xabbuh's feedback

Fixed missing new line

Removed superfluous comma.

Updated from feedback

Moved the list of events down in the listener and subscriber section

* Formatted the list as a table, exposing the constant values;
* Added references to the form event information table;
* Added caution sections for actions that should prevented while in each event.

Added the form_events link in the components map file, a.k.a. 'Added the missing link'

Added missing newlines

Added cross-reference in the form events cookbook

Updated based on Luis' feedback

Added tables describing the form and event values:

* Model data
* Normalized data
* View data
* Event data

Small fixes

Updated a few wordings to make them more clear

Changed important directive to caution

Removed sidebar section about form extensions.

Renamed ``{EVENT}`` to ``FormEvents::{EVENT}``, and added code snippet

Last small changes

Fixed underline too short