Create a system to alias non-standard tags to standard ones.  The only
currently defined tag aliases "bgcolor" to "background-color", but this
puts generalized system in place.
fix CSS parser breaking on "@media screen and ..."

Issue #132
The deltaHeight (which accounts for the vertical padding on the image) was being ignored, resulting in some large images crashing xhtml2pdf
Merge pull request #133 from khink/master

fix CSS parser breaking on "@media screen and ..."
Merge pull request #135 from tobynance/image-resizing

availHeight overwritten in _calcImageMaxSizes()
Allowing vertical barcode printing

Adding new tag attribute to print the barcode in vertical position
fixed issue #59
Merge pull request #140 from glomium/master

fixed issue #59
Merge pull request #139 from zot24/master

Allowing vertical barcode printing
Fixed canvas to new origin

Moving our canvas to the new origin when rotate it
Merge branch 'master' of https://github.com/chrisglass/xhtml2pdf
Merge pull request #142 from zot24/master

Fixed canvas to new origin
Replace pyPdf with PyPDF2 and fix readme
Merge pull request #148 from travelbird/master

Replace pyPdf with PyPDF2 and fix readme
Fix resource leaks by using weakrefs to avoid circular references.

Tested with pisa==3.0.33 (from PyPI) but the same circular reference
seems to exist here.

Reproducing:

Create a PDF with a (large) @page background PDF. Do this a couple of
times in a long running application and you'll see more and more file
handles reference the background-pdf. (That's just a symptom of objects
not getting garbage collected.)

After applying this fix, the file handles are released and the
excessive memory usage is gone. That leads us to believe that this
fixes the problems we were having.

In our case, when reproducing, we still had /some/ file handles open
after the fix, but an explicit call to `gc.collect()` cleared those too.
Merge pull request #152 from ossobv/osso-context-circular-refs

Fix resource leaks by using weakrefs to avoid circular references.
Merge pull request #131 from donbixler/master

Create a system to alias non-standard tags to standard ones.
Fix headers/footers in landscape mode.

Now you need to set a "is_landscape:1" line in your header and footer CSS in addition
to "size:a4 landscape" in the @page frame.
Quick fix to limit reportlab version range.

Version 3.0, if installed, will not be detected by xhtml2pdf, so define the reportlab dependency as a range (>=2.2, <3.0).
Merge pull request #157 from amcgregor/master

Quick fix to limit reportlab version range.