Fix the documented inheritance for GTK2.CellRendererSpin
Add property list for GTK2.CellRendererSpin
Enable more GTK2 constants
GTK2 docs: Add a space to the warning messages to make the output easier to parse
Fix warnings on GTK2 docs generation
Valgrind: suppress some warnings
block_allocator: do not keep empty pages around

In certain cases the block allocator kept around free pages. This
happened with markers used by the gc.
Some documentation tweaks
Disable the "new" constants for now. These seem to be Gnome1 only.
IOBuffer: Improved error recovery for read_h{string,buffer}().

Don't advance the buffer pointers if there's not enough data.

NB: Not a 100% robust. It will fail if io_avail() throws errors,
    or if the holerith length is negative or too large.
Always make the certificate the default certificate.
Signatures needs to be padded to the full size.