wb_intercon: assert wbm_err_o on non-match accesses

Instead of falling back to the first slave when no match occur,
signal a wishbone error. If fallback behaviour is desired,
it's still acheivable by extending the range of the slave
to which the fallback is desired.
avalon_to_wb_bridge: abort read on wbm_err_i
cores: add vga_lcd core

This adds the vga_cld core from opencores, with two accompanying
patches.
One for a typo of a signal and one for fifo auto resync.
Merge pull request #13 from skristiansson/for-openrisc

cores: updates fixes and additions