HACKING.asciidoc: add info about getting and building libam7xxx

Some Ubuntu user asked for a step by step guide.

• [DH] HACKING.asciidoc

README.asciidoc: add Royaltek PJU-2100 to the AM7XXX based devices list

The drivers for this device look like the same "EZ Display" bundle as
some other models.

• [DH] README.asciidoc

am7xxx: add support for Acer C112

• [DH] src/am7xxx.c

README.asciidoc document how to get libam7xx running on MS Windows

• [DH] README.asciidoc

Add a simple usb_mode_switch clone for am7xxx devices

Add am7xxx_mode_switch, this is will be used on systems where
usb_mode_switch is not easily available (e.g. MS Windows).

• [DH] examples/CMakeLists.txt
• [DH] examples/am7xxx_mode_switch.c

TODO: mention the plan about GStreamer

• [DH] TODO

Merge branch 'mingw-port'

• [DH] CMakeLists.txt
• [DH] HACKING.asciidoc
• [DH] cmake_modules/FindFFmpeg.cmake
• [DH] cmake_modules/mingw_cross_toolchain.cmake
• [DH] examples/CMakeLists.txt
• [DH] examples/picoproj.c
• [DH] src/CMakeLists.txt
• [DH] src/am7xxx.c
• [DH] src/serialize.c

HACKING.asciidoc: add a section to explain Windows cross compilation

• [DH] HACKING.asciidoc

Add a CMAKE_TOOLCHAIN_FILE to compile with MinGW

This is inspired by this blog post by Sylvain Beucler:
http://blog.beuc.net/posts/Cross-compiling_with_CMake/

• [DH] cmake_modules/mingw_cross_toolchain.cmake

Don't set -pedantic-errors in CMAKE_C_FLAGS, it breaks check_symbol_exists()

Set -pedantic-errors in more specific variables like
CMAKE_C_FLAGS_DEBUG, CMAKE_C_FLAGS_RELEASE and
CMAKE_C_FLAGS_RELWITHDEBINFO.

See also http://public.kitware.com/Bug/view.php?id=13208

• [DH] CMakeLists.txt

picoproj: replace mmap() with more portable file stream operations

This makes picoproj compile for Windows, for instance.

• [DH] examples/picoproj.c

picoproj: fix a typo

We have no am7xxx_get_info(), maybe this is a leftover of some older
unreleased API version.

• [DH] examples/picoproj.c

picoproj: issue a warning when passing "-f" more than once

• [DH] examples/picoproj.c

am7xxx: don't look for the math library when compiling for Windows

• [DH] src/CMakeLists.txt

am7xxx: MinGW does not have endian.h, provide fallbacks

Provide fallbacks only for the functions used in the code, and assume
Windows is always using little endian.

• [DH] src/serialize.c

am7xxx: fix setting the USB configuration

libusb_set_configuration() expects the bConfigurationValue of the
configuration we wish to activate as the second parameter.

The am7xxx devices we know have bConfigurationValue=2 for the first and
only configuration available in the descriptor, use this value.

While the libusb linux back-end looks forgiving on this one, without this
change the WinUSB back-end will fail with an error like:

C:\Documents and Settings\Administrator\Desktop\win>picoproj.exe -f image.jpg -F 1 -l 5 -W 800 -H 480
JPEG format
scan_devices: am7xxx device found, index: 0, name: Acer C110
[timestamp] [threadID] facility level [function call] <message>
--------------------------------------------------------------------------------

[ 0.000000] [00000eb0] libusbx: warning [winusb_submit_control_transfer] cannot set configuration other than the default one
[ 0.031250] [00000eb0] libusbx: warning [winusb_submit_control_transfer] cannot set configuration other than the default one
[ 0.046875] [00000eb0] libusbx: error [winusb_submit_bulk_transfer] unable to match endpoint to an open interface - cancelling transfer
read_data[281]: ret: -5 transferred: 0 (expected 24)
am7xxx_get_info: No such file or directory

• [DH] src/am7xxx.c

am7xxx: use hex notation for USB endpoints

This is for consistency with other uses.

• [DH] src/am7xxx.c

picoproj: use MAP_PRIVATE in the mmap call

There is no need to allow sharing the mapped region with other
processes.

• [DH] examples/picoproj.c

HACKING.asciidoc: fix cmake invocation examples

Put the path to the source dir last, like the cmake manual says:

  cmake [options] <path-to-source>

Also put a space between the -D option and the configuration setting it
modifies, this is more readable.

• [DH] HACKING.asciidoc

Merge remote-tracking branch 'origin/rettichschnidi' into mingw-port

• [DH] cmake_modules/FindFFmpeg.cmake
• [DH] examples/CMakeLists.txt