add and use git cleaning scripts

dotfiles/scripts/_git-list-fat

@@ -0,0 +1,13 @@
+#!/bin/sh
+
+git rev-list --all --objects | \
+    sed -n $(git rev-list --objects --all | \
+    cut -f1 -d' ' | \
+    git cat-file --batch-check | \
+    grep blob | \
+    sort -n -k 3 | \
+    tail -n40 | \
+    while read hash type size; do
+         echo -n "-e s/$hash/$size/p ";
+    done) | \
+    sort -n -k1

dotfiles/scripts/_git-rm-fat

@@ -0,0 +1,14 @@
+#!/bin/sh
+
+set -e
+
+read files
+
+git filter-branch -f  --index-filter \
+    "git rm --force --cached --ignore-unmatch $files" \
+     -- --all
+
+rm -Rf .git/refs/original && \
+    git reflog expire --expire=now --all && \
+    git gc --aggressive && \
+    git prune