This patch replaces the terminal's formerly built-in fonts with the new
VFS-based font handling.
To avoid the copying of the terminal's font configuration across run
scripts, this patch adds the new terminal/pkg runtime package, which
includes everything needed for instantiating a terminal: the actual
terminal component, the library dependencies (vfs_ttf, which in turn
depends on the libc), a font (bitstream-vera), and a reasonable default
configuration.
Fixes#2758
