[Console] Fixed unsetting of setted attributes on OutputFormatterStyle

Unset only previous setted styles in place of all styles, before this fix,
OutputFormatterStyle reset all attributes with '\e[0m' sequence.
Now, if a foreground is setted, reset only the foreground so you can use innested attributes

Conflicts:
	src/Symfony/Component/Console/Tests/Formatter/OutputFormatterStyleTest.php
	src/Symfony/Component/Console/Tests/Formatter/OutputFormatterTest.php
	src/Symfony/Component/Console/Tests/Output/OutputTest.php
feature #10476 [Console] Fixed unsetting of setted attributes on OutputFormatterStyle (Badkill)

This PR was merged into the 2.5-dev branch.

Discussion
----------

[Console] Fixed unsetting of setted attributes on OutputFormatterStyle

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | yes
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | none
| License       | MIT
| Doc PR        | none

Unset only previous setted styles in place of all styles, before this fix,
OutputFormatterStyle reset all attributes with '\e[0m' sequence.
Now, if a foreground is setted, reset only the foreground so you can use innested attributes

Conflicts:
	src/Symfony/Component/Console/Tests/Formatter/OutputFormatterStyleTest.php
	src/Symfony/Component/Console/Tests/Formatter/OutputFormatterTest.php
	src/Symfony/Component/Console/Tests/Output/OutputTest.php

Commits
-------

ce0c4b4 [Console] Fixed unsetting of setted attributes on OutputFormatterStyle