Rebase against upstream

Enables Symfony 4 support

Rebased against upstream

2.0.2

Handle placeholder attribute better

Improve placeholder extraction

Correctly take into account translation_domain when extracting placeholder

Rebased against upstream, refactored and redid most changes.

2.0.0

Merge branch 'add-options-to-disable-date-source'

Fix case where choices might not have keys

1.2.4

Ignore cases where key is missing

Rebased against upstream repo

1.2.3

Updated tests for Symfony 3.0

Option to remove source files from xliff output

This release adds option to configure xliff output, including

• Remove date from output file
• Remove source file lines from output

Updates to form extractor

• Form extractor now considers choice_translation_domain when extracting choices
• Extractor skips translations if translation_domain or choice_translation_domain is false