backends: Improve Linux FB backend.

Signed-off-by: Cyril Hrubis <metan@ucw.cz>
demos: c_simple, particle: Add -b (backend) option

This allows specifying backend init string with -b option.

Signed-off-by: Cyril Hrubis <metan@ucw.cz>
backends: Add basic AALib backend.

Unfortunately aalib is not thread safe nor it exposes file descriptor so
we have to stick to polling as we need to be thread safe.

Signed-off-by: Cyril Hrubis <metan@ucw.cz>
demos: Add backend resize ack to few demos

Add backend resize ack and system exit handling to linetest and
shapetest and particle demo.

Signed-off-by: Cyril Hrubis <metan@ucw.cz>
input: KBD: Add mapping for few keys.

These are arrows, delete, left meta and sysrq.

Now works on your framebuffer too ;).

Signed-off-by: Cyril Hrubis <metan@ucw.cz>
backends: SDL: Avoid lockup in Wait.

Same story again. We cannot sleep in Wait while holding the mutex and we
do not have a file descriptor to poll on so we need resort to polling.

We will need a better solution here.

One posibility is to add a init flag to all backends and resort to
polling only if application needs thread safe backend.

Signed-off-by: Cyril Hrubis <metan@ucw.cz>
core: GP_Common.h: Add stddef.h due to offsetof().

Signed-off-by: Cyril Hrubis <metan@ucw.cz>
input: KBD: Remove newline from debug message.

Signed-off-by: Cyril Hrubis <metan@ucw.cz>
filters: GP_ResizeLinear.gen.c.t: Remove debug print

Remove forgotten debug printf.

Signed-off-by: Cyril Hrubis <metan@ucw.cz>
spiv: Disable timers by default.

Timers are disabled by default and can be enabled with -t.

Timers prints cpu and wall time for certain operation into the stdout.

Signed-off-by: Cyril Hrubis <metan@ucw.cz>