lkmc v2-rc

Unsquashed version at v2-rc-unsquashed, but that cannot be merged as it
breaks bisects at several points. All bugs will not bisect to this
humongous change.

It all started with a conversion of the Bash scripts to Python, mainly
because I couldn't stand not being able to properly use --options for
run which has a million options.

Then since that required a full testing, I decided to do all the
refactorings that I had in mind at once, and so I did and it became
v2-rc.

This is the largest patch I have ever done! OMG a few weeks of extra time.
I'm never writing a Bash script for anything that starts getting big again.

Some of the features are:

* separate build-qemu and build-gem5 commands
* common: convert scripts to python. Add --option for everything
* rename build to build-buildroot now that we are splitting all the build
  commands, Linux kernel to follow
* move all git submodules to submodules/ and all buildroot packages to
  packages/
* refactor the out/ structure. Keep projects on toplevel, because guest
  projects separate archs and host ones don't, making a toplevel arch wrong
* do-release: rename to just release
  https://stackoverflow.com/questions/16174992/cant-get-argparse-to-read-quoted-string-with-dashes-in-it
* run: add --terminal and explain gem5 pdb
* just track the lvimrc
* store CLI kernel config fragment inside buildlroot to avoid conflicts
* gem5: document m5 initparam
* readme: make a bunch of things awesomer
* readme: fix broken refs
* parsec-benchmark: update to 75d55ac446a43c47efb1044844a108c6c330184c
  Could not fetch otherwise.
* gem5: M5_OVERRIDE_PY_SOURCE

.gitmodules

@@ -1,16 +1,20 @@
-[submodule "buildroot"]
-	path = buildroot
+[submodule "submodules/buildroot"]
+	path = submodules/buildroot
 	url = https://github.com/cirosantilli/buildroot
 	ignore = dirty
-[submodule "qemu"]
-	path = qemu
+[submodule "submodules/qemu"]
+	path = submodules/qemu
 	url = https://github.com/cirosantilli/qemu
-[submodule "linux"]
-	path = linux
+# The true upstream does not accept git submodule update --init --depth 1
+# git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
+# But git clone --branch --depth 1 worked weirdly:
+# https://unix.stackexchange.com/questions/338578/linux-kernel-source-code-size-difference
+[submodule "submodules/linux"]
+	path = submodules/linux
 	url = https://github.com/cirosantilli/linux
-[submodule "gem5/gem5"]
-	path = gem5/gem5
+[submodule "submodules/gem5"]
+	path = submodules/gem5
 	url = https://gem5.googlesource.com/public/gem5
-[submodule "parsec-benchmark/parsec-benchmark"]
-	path = parsec-benchmark/parsec-benchmark
+[submodule "submodules/parsec-benchmark"]
+	path = submodules/parsec-benchmark
 	url = https://github.com/cirosantilli/parsec-benchmark