repo: Import Google's repo tool

Add submodule a ~/opt/git-repo of my fork of git-repo. Link the main script to
~/bin/repo.
make: Add missing dep on TARGET_DIR

~/bin 'install' depends on ~/bin.
vim; Add wrapper scripts vimclient,gvimclient
kw-whitespace: Import whitespace scripts

kw-whitespace-eof-nl
kw-whitespace-trim
kw-find: Import scripts kw-find-rcs, kw-find-src
build: Create new build system like Android's

- Import android/build/tools/findleaves.py.
- Partially import android/build/core/definitions.mk as _build/functions.mk.
- Partially import android/build/core/clear_vars.mk.
- Create a custom _build/{core.mk,install_module.mk}, tailored for this project.
build: Migrate to new build system

This build system is more modular and declarative than before.

The big advantages are:
    - Low risk of merge conflicts in Makefiles when merging the public branch
      into private branches.
    - Shorter, less repetitive makefiles.

The install step has changed:
    OLD: make -f Home.mk
    NEW: make install
build: Fix the 'files' install method

When LOCAL_INSTALL_METHOD = "files", we failed to create a dependency rule for
install-$(LOCAL_MODULE), and so we installed nothing for that module.
systemd: Import user session units v8 from Auke Kok

Import from git://github.com/sofar/user-session-units.git#refs/tags/v8 .
systemd: Add services for standard gnome components

gnome-screensaver
gnome-settings-daemon
gnome-sound-applet
notification-daemon
systemd: Add nm-applet service
systemd: Add tint2 service
systemd: Add xcompmgr service
systemd: Add gtk-redshift service
service: Add virtual panel.target
systemd: Add virtual kiwi-desktop.target
systemd: Add empty, virtual kiwi-desktop.target
gnome-session: Fix null session

A gnome session must have some RequiredProviders and RequiredComponents.
Otherwise, otherwise you get the Fail Whale Sad Face screen.
gnome-session: Choose null.session

This prepares for switching over to systemd user sessions. There, the gnome
session will not spawn any DefaultProvides or RequiredComponents, so the session
file should be nearly empty. Systemd will spawn those as services.