Added tb_tb_tb_eth.vhd to simulate eth for multiple technologies (currently only stratixiv).

- Use common_network_layers_pkg from common (was eth_layers in $UNB)
- Use tech_tse_pkg and tb_tech_tse_pkg from tech_tse_lib (was work=tse_lib in $UNB)

Use ip_<device name> directories instead of following the altera/altera_mf library namings.
Move all Altera IP for Stratix IV to ip_stratixiv/ and use prefix ip_stratixiv_<component_name> for the IP files.
Remove xilinx/xilinx_core directory. Instead added ip_virtex4/ directory with empty hdllib.cfg.

Ported common RAM, ROM components from /home/kooistra/svnroot/UniBoard_FP7/UniBoard/trunk to /home/kooistra/svnroot/UniBoard_FP7/RadioHDL/trunk.