Move all the FTDI MPSSE definitions and helpers into a separate
ftdi-mpsse crate. Update FtdiMpsse implementation using command
builder from ftdi-mpsse crate. Re-export definitions from the
new crate to reduce the number of breaking changes.

Signed-off-by: Sergey Matyukevich <[email protected]>

Use compile-time mpsse! macros for simple commands with
fixed parameters to save a call to malloc.

Signed-off-by: Sergey Matyukevich <[email protected]>

Use ftdi-mpsse helpers to build MPSSE clock configuration commands.

Signed-off-by: Sergey Matyukevich <[email protected]>

Implement Drop trait for Ftdi structure to make sure that FTDI device is
properly closed. For this purpose embed Ftdi into Ftx232h. Otherwise the
original Ftdi structure is dropped after new Ftx232h structure iscreated.
As a result, drop method is called, FTDI device is closed and can not be
used by the newly created Ftx232h.

Signed-off-by: Sergey Matyukevich <[email protected]>

The ftdi-mpsse crate defines MpsseCmdExecutor trait. The trait
describes basic operations required to work with MPSSE engine
on FTDI chip. This commit implements MpsseCmdExecutor for all
the FtdiMpsse types provided by libftd2xx.

Signed-off-by: Sergey Matyukevich <[email protected]>

RFC: move mpsse helpers to the separate ftdi-mpsse crate