Perform file tokenization in python

[WhatAmISupposedToPutHere]

Avoid going through bash and perl just to run some regexes. No existing project files override those functions, so no functionality is lost.

update.py speed comparison on a clean import of arm-trusted-firmware

before:
real 21m53.464s
user 49m20.962s
sys 30m0.147s

after:
real 21m5.273s
user 44m39.705s
sys 26m11.396s

[tleb]

Hi, yes I'm down for this. But it completely breaks file rendering. All files appear as a single empty line. Agreed?

---

Reproducer:

⟩ git checkout -q -f 9ae8062

⟩ # change musl repo because it's inaccessible and fetch a single tag
⟩ git diff -U0 utils/index
diff --git a/utils/index b/utils/index
index 3298a87..6f7f15f 100755
--- a/utils/index
+++ b/utils/index
@@ -47 +47 @@ project_fetch() {
-    $git fetch --all --tags -j4
+    $git fetch --no-tags remote0 +refs/tags/v1.2.6:refs/tags/v1.2.6
@@ -128 +128 @@ add_default_remotes $1 $# $2 mesa https://gitlab.freedesktop.org/mesa/mesa.git
-add_default_remotes $1 $# $2 musl https://git.musl-libc.org/git/musl
+add_default_remotes $1 $# $2 musl https://github.com/kraj/musl.git

⟩ docker build -q -t elixir-repro -f docker/Dockerfile .
⟩ sudo rm -rf data/

⟩ docker run --rm -v ./data:/srv/elixir-data --entrypoint index \
  elixir-repro /srv/elixir-data musl
... indexes v1.2.6 ...

⟩ docker run -d --name lxr-t -p 8080:80 -v ./data:/srv/elixir-data elixir-repro
⟩ curl -s http://localhost:8080/musl/v1.2.6/source/crt/crt1.c | grep -c 'codeline'
1

⟩ # => the whole file renders as one empty line; on master: 19 code lines,
⟩ # 8 ident links

[WhatAmISupposedToPutHere]

Oops, sorry about that, it appears that i failed at rebasing this from my dev branch. Should render correctly now.