Update external/hidapi reference to latest upstream
Report update errors in threaded LED writing mode

The reporting is delayed, but better than pretending success.
Cherry-pick a fix from upstream PS3EYEDriver
Revert external/hidapi to an older commit

The previous update to the latest hidapi upstream introduced changes that
break HID Feature reports on Windows. This fix sets the hidapi submodule to
the commit preceeding the problematic one.

For a description of the problem see hidapi's issue list:

  https://github.com/signal11/hidapi/issues/192
Merge pull request #134 from nitsch/rollback-hidapi

Revert external/hidapi to an older commit
Add links to EXT device documentation
Add detection for Sharp Shooter's pump action
Fix EXT device report buffer size

This makes the EXT device support work on Windows.
Add missing line breaks in debug output
Merge pull request #135 from nitsch/improve-ext

Improve EXT device support
Update Windows build to MinGW-w64 4.9.1

Since different versions of MinGW-w64 differ in support of clock-related
functions, we do now suggest using version 4.9.1 which was tested on
several Windows systems.

This fix removes the now obsolete redefinitions of unsupported clock
features and gives detailed instructions in the README for fetching the
correct version of MinGW for Windows builds.
Cut down on automatic header inclusion on Windows

This will prevent windows.h from dragging in lots of other header files
by default. It helps us avoid problems such as having to include
winsock2.h before windows.h which would otherwise lead to problems with
redefined symbols.
Remove -fPIC for builds on Windows

We recommend using MinGW-w64 for the Windows builds which generates
position-independent code by default. Removing the -fPIC option gets
rid of the warning that reminds of this behaviour.
Fix weird numbering in Windows README file
Remove hh modifier from format strings

MinGW does not support C99's hh modifier in format strings (likely for
compatibility with Microsoft's compiler). This fix replaces the modifier
with a cast of char arguments to unsigned char to achive the same result.