While it was a great idea, various g-i based bindings don't support
GArray with entries greater than sizeof(gpointer) :(
So let's just make everybody happy by just using GPtrArray.
And since we're breaking the API, also rename the various descriptor fields
to no longer have the descriptor_ prefix.
It does cost a bit more in terms of memory/cpu usage, but makes it usable
from bindings.
* Add a base page for the library
* Add pages for the base MPEG-TS section and descriptors
* Add pages for the known variants
* Add documentation on more fields/sections/types
* Remove some fixmes that were ... fixed