Added MusicActivityHud#z, a position exposure

It was a long overdue thing to be done.
#x, #y, and #z have all been exposed and can be modified
to move the Hud around.
Merge branch 'master' of https://github.com/archSeer/moon into ice-dev
Prefer one line access for @event_listener hash

Instead of referencing the same (key) twice, reference once, create
an Array if neccessary and then push the (block) as needed.
Added the Input::Keyboard sub-module

It has been a itching issue, with having Input.modded?
and then seeing Input::Mouse.modded?
You would immediately ask, what exactly is Input?
Input was, actually the keyboard.
In exchange for a few extra characters, Input::Keyboard is the
replacement.

Summary:
All Input functions have been moved to Input::Keyboard
Moved State_ModifierTest::BUTTONS to Input::Mouse

BUTTONS was in the wrong place to begin with.
With this, it should be easier to enumerate the Mouse buttons, to
test all of them for input if necessary.
States now use Input::Keyboard instead of Input
Fixed deprecated conversion, compiler warning

"warning: deprecated conversion from string constant to 'char*' [-Wwrite-strings]"
Silenced that annoying error while compiling the Input code.
While the fix is a bit, unsafe it works for now:
since none of the names go over the 24 character limit
Revert "Fixed deprecated conversion, compiler warning"

This reverts commit d8fa7acaf561228567d2ef4fcd6990020c920eb9.
proper fix for -Wwrite-strings.

string constants need to be cast to const char*, not char* -- still
need to be constant. Compiler allows us to cast them to char*, but
throws a warning, because editing a constant later would exhibit
undefined behavior.
Merge pull request #1 from archSeer/ice-dev

Ice dev