[3dprinter-general] Bug#1050157: Reassign and raise severity

[Gregor Riepl]

> Reassigning to `pronterface` since it doesn't really affect the full
> printrun suite. `plater` suffers the exact same issue but neither
> `pronsole` nor `printcore` do.
Unfortunately, the bug still affects src:printrun (and therefore all other binary packages).

In order to keep the package in Debian, plater and pronterface need to be disabled in the build, together with the dependency on pyglet.