This fontmeta struct is not only intended for use in a gly file,
   but also for use in a fontselect program.
Debian has several fontselect programs already,
   but none of these allows you to select a font that is not already installed.
So i plan to have time to make gly files of all fonts that Debian provides
   and make a jpeg of first few characters of each font,
   for a manual fontselection program.
Also, if a webserver encounters characters that it can not display
   because X has not loaded a font that contains a glyph for it
   such a fontselect could automatically load a suitable font.

A shortcoming of X is that
   it does not tell which glyphs in a range of characters a font does not have,
   which results in a 'default' character being displayed in that case,
   without application being aware of that.
For example : for font MiscFixed20re75, X reports that it contains 65000 characters,
   but in reality it contains only 5012 non-default glyphs.
My program that grabs glyph shapes from X and puts them in a gly file
   uses a simple heuristic to detect default shapes,
   and does not include these glyphs for these characters.
(This program is not part of canvas source, and is work in sometimes progress).

This glyphmeta struct is spin-off of one of my other projects,
   and is preliminary.
Problems that still need to be addressed are :
* how to encode glyphs that are not in basic multilingual plane of unicode
   (probably by increasing datasize of 'character' member of glyphmeta),
* how to deal with fonts that have other known encodings, eg iso8859-2
   (probably by converting everything to unicode).
* how to support different drawing directions
   (probably by indicating them in one of unused members,
   and updating documentation to tell what meanings of fields then are).

logiwi is same as 'stride'.
data is offset of glyphdata, from start of file, in bytes.

Inkmaps do not have a struct, but are arrays ;
   number of elements in array can be found from inkbox sizes.
bwmap is an array of bits, value 1 indicating 'inked',
   stored in an array of uchar
   where most significant bit represents leftmost pixel.
grymap is an array of 4bit values, stored in uchar,
   value indicating inkedness,
   highest valued nibble containing inkedness of leftmost pixel.

Toggles

A 'toggle' contains an inkedness value and a repeat count.
Thus each toggle represents inkedness of a series of identically inked pixels.
Just as with inkmaps, there are as many toggles as are needed to fill inkbox.

Bwtoggle

For black&white fonts,
   bwmap is smallest storage size,
   for fonts who'se average character width is not more than 32 pixels.
A full unicode BMP font of 32-pixels-wide characters is circa 8 MB .
For larger fonts, bwtoggle is smaller.

For gry-scale fonts,
   gry toggle is smallest storage size,
   for fonts who'se average character width is not more than 32 pixels.
A full unicode BMP font of 32-pixels-wide characters is circa 18 MB .
For larger fonts, ttf fileformat is smaller
   (if size of kerning information is small compared to glyphdata).

Grymap is thus not smallest format for any font size.

Sizes mentioned above are for font files,
   but this is not quite same as storage size of a font that is loaded by X.
Some applications use glyph caches,
   so i assume that they store valuemaps of glyph shapes
     which are not smaller (and probably larger) than grytoggles
   to save time on rendering font shapes from vector descriptions.
Here grytoggle has an advantage, because it is an on-the-fly decompressible format.
This also makes glyfiles easy to use :
   to load a font, all you need to do is to mmap it
   (using a private mmap, preferably, to not risk accidentally overwriting it).

For bitmapped fonts, filesize of gly files is less than half of that of bdf files,
   but after gzipping, difference is much smaller.