tweaked Twig introduction
[book] Fixed every inconsistention find in quick proofread
Some fixes
fixing doctrine dbal mapping types xml,php tabs
[Cookbook] [Data Collector] Add missing "Bundle"
[#814] [Form] Added documentation for Form Type Extensions
[#814] [Form] Fine-tuned punctuations and style
[#814] [Form] Added html+php syntax
Added a cookbook entry about building single command applications

This documents the way to achieve the use case requested in
symfony/symfony#3857
Updated README file with the new branch

There is a new `2.1` branch for some months now, we should update the README file to include this branch (and new features).
Add missing parameter

The file array was missing
[Cookbook/configuration] Changed warning box to caution
remove unwanted comma
This abbreviation felt sloppy; write like a sir
Add some punctuation here and there.
Try to produce something easier to understand.
avoid awkward awkward construction
Add some punctuation
It does not feel right without -ing
Improve formatting