make my dotfiles location independent

This is achieved by storing the absolute path to the dotfile directory in the
variable $DOTFILES_LOCATION. And change every hardcoded location into the
dotfiles with this var.
The Variable $DOTFILES_LOCATION populated with the output of
get_dotfiles_location.sh at 3 places:   1) config.fish | zshrc
                                        2) xinitrc (should be allready exported)

get_dotfiles_location uses the assumption that it is symlinked into the dotfiles
directory.

offlineimap:    * include patch for offlineimap
                * change config to the small one
                * include environment file in systemd unit

setup.py:       * handle offlineimap situation
                    * print a warning and prompt for proceeding
                    * write the environment file for the systemd unit
                * add pseudo dependency (get_dotfiles_location)
                    to [fish-config, offlineimap, i3]
                * print errors on stderr
                * don't exit if a function fails

config.fish:    * export $DOTFILES_LOCATION
                * change hardcoded links
                * add perl tools to path
                * export some yaourt specific vars if yaourt is available

zshrc: export $DOTFILES_LOCATION

xinitrc: export $DOTFILES_LOCATION

i3/*: change hardcoded links

scripts/* change hardcoded links

README.md: mention $DOTFILES_LOCATION

1 files changed, 23 insertions, 4 deletions

diff --git a/README.md b/README.md
index ac5a6dd..2ff0c0b 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,26 @@
 ---
 
 ## Installation
-Some scripts use a hardcoded location so please locate the dotfile repo
-at $HOME/.dotfiles.  
-To do this run
-```git clone https://github.com/fischerling/dotfiles $HOME/.dotfiles```.
+
+For some scripts/snippets you don't know where they will be executed.
+Whenever a absolute path into the dotfile directory is needed the environment
+variable `DOTFILES_LOCATION` is used.
+
+The variable is exported in zshrc or config.fish or xinitrc.
+If you don't set it that way, please remember to export `DOTFILES_LOCATION`
+somewhere else.
+
+Good places are:
+
++ shell configs
++ at session start
+
+
+### Easy Installation
+
+If you just want to install all my dotfiles without customisation run:
+```sh
+git clone https://github.com/fischerling/dotfiles ~/.dotfiles
+cd ~/.dotfiles
+./setup.py
+```