handle Tj and TJ in content processor
viewer: render pdf page via imagemagick
viewer: options to render pdf, text and glyphs
scale glyphs according font size
content processor: user one function in instead of font map

Processor is not interested actually in fonts, so lets delegate
glyph decoding to higher level.

Also few haddock comments were added
oops: delete dead code
content processor: separate glyph's width bounding box

actually width can't be calculated from bounding box,
so we need to handle then separately
viewer: handle glyph widths array if presents

so, now we can correctly position glyphs, at least if the font
contains widths array.
viewer: use glyph width as it's bounding box width

It is not correct, but we don't have better source for
that info right now