Client|Resources: Added a separate resource pack for lens flares

Previously part of the core renderer.pack, however it is beneficial to
have it as a separate pack for customization.
Refactor|Resources: Organized shaders in renderer.pack

Now that Info has an @include directive, the shader definitions can
be organized more elegantly.
Client|FX|LensFlares: Updated to use lensflares.pack
Cleanup|Input|API: Deleted obsolete key repeater code, bumped B API
Cleanup|Input: Keymap files are obsolete

These haven't been used after the switch to Qt input.