use std::map instead of a specific template (CHash).
There is no need for special template. Moreover, using
std::map will allow easy iteration over the surfaces.
When a message has been read from the network we now pass it into
the generated demarshaller for the channel. The demarshaller converts
the network data to in-memory structures that is passed on to the
spice internals.
Additionally it also:
* Converts endianness
* Validates sizes of message and any pointers in it
* Localizes offsets (converts them to pointers)
* Checks for zero offsets in messages where they are not supported
Some of this was previously done using custom code in the client, this
is now removed.
1) add an option to determine if a bitmap can be sent lossy to the client
2) when required, replacing lossy cache items with their correspending
lossless bitmaps
Instead of having two virtualizations of the canvas we push the
virtualization into the canvas code itself. This not only avoids
the duplication of this code, it also makes the exposed API for the
canvas much smaller (in terms of exported API).
It also lets us use the virtualization to implement basic support
for operations in canvas_base which is then overridden by each canvas
implementation.
Instead of passing a bunch of function pointer and an opaque
pointer we make a real type and add a vtable pointer to it.
This means we can simplify all the canvas constructors, etc.
