Consolidate core implementing memoryless devices in one module; added
support for gain and envelopes and periodic => rumble conversion.

Signed-off-by: Anssi Hannula <anssi.hannula@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

Implement a new force feedback interface, in which all non-driver-specific
operations are separated to a common module. This includes handling effect
type validations, locking, etc.

The effects are now file descriptor specific instead of the previous strange
half-process half-fd specific behaviour. The effect memory of devices is not
emptied if the root user opens and closes the device while another user is
using effects. This is a minor change and most likely no force feedback
aware programs are affected by this negatively.

Otherwise the userspace interface is left unaltered.

Signed-off-by: Anssi Hannula <anssi.hannula@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

This will allow building input core module from several files
which is needed for the reworked force feedback support.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!