Removed croak in favor of the generally preferred carp
Slide content now accepts plain coderefs
Made return value of render_two_columns context aware
Added rather minimal support for a notes window
Increased the sampling resolution for latex rendering
Improved alignment inheritance and vastly improvied font hash handling

In particular, I finally bit the bullet and figured out how to merge
font hashes. In the process, I also vastly expanded the size and
height specs that can be used for fonts in renderables! I also
deprecated the font_factor field for paragraphs, since that can
now be achieved with the new font size spec handling. For example,
to achieve the old font_factor => 1.2, use font => { size => '1.2x' }
Added a few widgets as renderables