provider: add "url" provider

This patch add support for a new provider type "url".
It is now possible to fetch cores from url.
For example:

[provider]
name = url
url = http://nicecores.net/or2400.v
filetype = simple
corename = or2400

Signed-off-by: Franck Jullien <franck.jullien@gmail.com>
simulator.py: Handle several cores registering the same plusarg
[v2] Add a system programming option (pgm)

This patch adds an option to program your fpga from orpsoc.
Arguments specific to the backend programing tool can be
passed from orpsoc, for example:

      orpsoc pgm de1 --cable"USB-Blaster [2-1]"

Signed-off-by: Franck Jullien <franck.jullien@gmail.com>
Makefile.am: add missing file (url.py)

Signed-off-by: Franck Jullien <franck.jullien@gmail.com>
Makefile.am: add missing file (url.py)

Signed-off-by: Franck Jullien <franck.jullien@gmail.com>
Merge pull request #5 from fjullien/for-openrisc-new

Makefile.am: add missing file (url.py)
Merge branch 'master' of github.com:openrisc/orpsoc
Prepare for release
Improve handing of broken core description files

Instead of failing or silently ignoring various errors in the core
description files, a warning is now issued
Refactoring of build system

Move contents of build.py to proper packages and subclasses to
prepare for other backends
Merge branch 'master' of https://github.com/openrisc/orpsoc