apps/netutils/tftpc:  This commit modifies the TFTP client functions to use a data read/write callback instead of a file.This allows TFTP to write to arbitrary destination (in my case, a MTD device - for firmware update).  Two new functions are introduced for this, named tftpget_cb and tftpput_cb. They are just made of most of the existing code.  The previously existing tftpget/tftpput functions are now wrappers on the new ones, with callbacks that read/write from files, so my modifications are backwards compatible with existing applications, eg the associated nsh commands dont need to be changed.

apps/graphics/ft80x:  Add controls for enabling/disabling the audio amplifier; Add general interfaces for controlling FT80x GPIOs.

apps/graphics/ft80x:  Add basic support for GPIO and configuration for eventual support of FT80x GPIO audio shutdown controls

apps/graphics/ft80x:  Add interface to play midi sounds; apps/examples/ft80x:  Add an example using stencils.

apps/graphics/ft80x and apps/examples/ft80x:  Fix some compile issues with other configuration options are selected.

apps/graphics/ft80x:  Add more touchscreen interfaces.  apps/examples/ft80x:  Add an interactive example using buttons, keys, and touchscreen input.

apps/graphics/ft80x:  Add interfaces to control the backlight.  apps/examples/ft80x:  Fade the display on and off between each example.

apps/graphics/ft80x:  Add capabilitilies to send commands to the co-processor outside of the context of a display list.  apps/examples/ft80x:  Add another copressor example.. spinner animation.

apps/graphics/ft80x:  Add routine to wait for logo animation to complete.  apps/examples/ft80x:  Add more graphic demonstrations.

apps/graphics/ft80x:  Add support for reading/writing multiple registers.  Add interface to obtain the touchscreen transform matrix.  apps/examples/ft80x:  Add more co-processor demos.

    apps/examples/ft80x:  Add another co-processor demo
    ft80x: Add a few more debug message.

    apps/graphics/ft80x:  Replace polling logic with gentler signal logic when waitinf for the CMD FIFO to become empty.
    apps/examples/ft80x:  Add first co-processor example.
    apps/graphics:  Extend library to manage display lists either in display memory (RAM DL) or provided directly to th co-processor FIFO (RAM CMD).
    apps/examples/ft80x:  Some minor clean-up.  Trivial changes for coprocessor support.

Added ECANCELED condition to DEBUGASSERT-s checking sem_wait result

Approved-by: Gregory Nutt <gnutt@nuttx.org>

apps/graphics/ft80x and apps/examples/ft80x:  Fix a few compile-relate issues introduced with last merge.

    apps/graphics/ft80x:  Add support for accessing graphics ram.  apps/examples/ft80x:  Add more primitive graphics demos.
    apps/examples/ft80x:  Add a couple more demos of primitives.  Use new ft80x_dl_create() to simplify.
    apps/graphics/ft80x:  Add ft80x_dl_create() which simplies writing of very simple display lists.

    apps/examples/ft80x:  Add one display example.  Many more are needed but this is enough to get started with testing (when I eventually have hardware).
    apps/examples/ft80x:  Add the bare framework for a test of the FT80x

apps/graphics/ft80x:  Add the beginning of FT80x support library.  So far consists only of some display list helpers.