hid.cpp: Fixed crash when updating pad data while null

Fixes #137
Add a Doxygen configuration file to generate source docs
Fix compile errors in Clang
Add `override` keyword through the code.

This was automated using `clang-modernize`.
Merge pull request #153 from yuriks/add-override

Add override keyword where appropriate
Merge pull request #152 from yuriks/doxyfile

Add a Doxygen configuration file to generate source docs
Merge pull request #141 from archshift/crash-hunt

hid.cpp: Fixed crash when updating pad data while null
Use configuration files to enable or disable the new dyncom interpreter.
Added `gpu_refresh_rate` config setting for the new interpreter speed hack.
Merge pull request #151 from archshift/dyncom-enabled

Use configuration files to enable or disable the new dyncom interpreter.
Changed debugger font to Courier
Merge branch 'master' of https://github.com/Gareth422/citra