systems/de0_nano: fix .system syntax

Remove simulation related options

Signed-off-by: Franck Jullien <franck.jullien@gmail.com>
systems/de1: fix .core and .system syntax

de1.core:

- remove leading spaces from simulator options
- add modelsim to the list of supported simulator

de1.system:

- Remove simulator related options

Signed-off-by: Franck Jullien <franck.jullien@gmail.com>
cores: add opencores ac97 controller core
cores: add opencores i2c master controller core
Merge pull request #19 from skristiansson/for-openrisc

core additions
de0_nano: remove non-existing altera_virtual_jtag.v from src_files
Merge branch 'de0_nano' of github.com:skristiansson/orpsoc-cores into de0_nano