newFont with missing file throws exception

Issue #115 resolved
Boolsheet
created an issue

It appears there's no 'file does exists' check before f->read() in //src/modules/graphics/opengl/wrap_Graphics.cpp// on line 216.
\\
Trying to call love.graphics.newFont("does_not_exists.ttf") throws an exception and LÖVE terminates.\
love.graphics.newImage throws a Lua error in this situation.