[Security][Acl] Issue #5787 : Added MutableAclProvider::deleteSecurityIdentity

Code style fix and documentation typo
adds support for PTY mode
adds convenience method mustRun
attempts to fix tests on Travis
adds cache for isPtySupported()
remove deprecated constraints calls (Min, Max, MaxLength, MinLength)
[Form] Fixed memory leak in FormValidator
[Console] make parent constructor test more reliable

it also fixes the test since f2b60e9c687 and improves phpdoc
[Console] improve regex performance to validate name

using possesive quantifier
Set the font-weight for links to 'normal', to prevent ugly bold links.
[Intl] make currency bundle merge fallback locales when accessing data, allowing use of country-specific locales
Fix finder date constraints and tests
[Routing] added working test case for issue #5135
[Process] Renamed flushOutput() and flushErrorOutput() to clearOutput() and clearErrorOutput()
added content length header to BinaryFileResponse
bug #9412 [HttpFoundation] added content length header to BinaryFileResponse (kbond)

This PR was submitted for the master branch but it was merged into the 2.2 branch instead (closes #9412).

Discussion
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[HttpFoundation] added content length header to BinaryFileResponse

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #9256, #7684
| License       | MIT
| Doc PR        | n/a

Commits
-------

e75a556 added content length header to BinaryFileResponse
Add X-Debug-Url profiler url header
update CONTRIBUTORS
fixed issue with clone now the children of the original form are preserved and the clone form is given new children
[Form] fix CsrfProviderAdapter