Add image import (hey, totally untested, but I thought I should push it :p)

Finish up basics to create first PDF document

Add tests for NullEncryption

Add bitmask class to simplify permissions class

Some minor scrutinizer fixes

Lots of cleanup and a little bit more refactoring

Add unit tests for the object writer plus a few benchmarks

Fix minor mistakes pointed out by scrutinizer

Temporarily fix coveralls until new version of php-coveralls is tagged

Add unit tests for encryption

Merge pull request #6 from Xerkus/patch-2

Add tests to cs checks and disallow long array syntax

Merge pull request #4 from Xerkus/patch-1

Make phpunit a bit stricter

Some more work on the PdfWriter class (methods may be moved later)