[split] Move bira theme to oh-my-fish/theme-bira

https://github.com/oh-my-fish/theme-bira

themes/bira/README.md

-## bira
-
-Theme imported from Oh my ZSH: https://github.com/robbyrussell/oh-my-zsh/blob/master/themes/bira.zsh-theme
-Contains traces of nuts and code from other Oh my fish themes.
-
-Display username, hostname, current path, ruby version and git status. Display the latest error status in the right prompt.
-
-![bira theme](https://cloud.githubusercontent.com/assets/1214238/5441541/8bd494dc-8491-11e4-9dbe-256b7e558eac.png)
-
-TODO:
- - display Python version

themes/bira/fish_prompt.fish

-# Theme based on Bira theme from oh-my-zsh: https://github.com/robbyrussell/oh-my-zsh/blob/master/themes/bira.zsh-theme
-# Some code stolen from oh-my-fish clearance theme: https://github.com/bpinto/oh-my-fish/blob/master/themes/clearance/
-
-function __user_host
-  set -l content 
-  if [ (id -u) = "0" ];
-    echo -n (set_color --bold red)
-  else
-    echo -n (set_color --bold green)
-  end
-  echo -n $USER@(hostname|cut -d . -f 1) (set color normal)
-end
-
-function __current_path
-  echo -n (set_color --bold blue) (pwd) (set_color normal) 
-end
-
-function _git_branch_name
-  echo (command git symbolic-ref HEAD ^/dev/null | sed -e 's|^refs/heads/||')
-end
-
-function _git_is_dirty
-  echo (command git status -s --ignore-submodules=dirty ^/dev/null)
-end
-
-function __git_status
-  if [ (_git_branch_name) ]
-    set -l git_branch (_git_branch_name)
-
-    if [ (_git_is_dirty) ]
-      set git_info '<'$git_branch"*"'>'
-    else
-      set git_info '<'$git_branch'>'
-    end
-
-    echo -n (set_color yellow) $git_info (set_color normal) 
-  end
-end
-
-function __ruby_version
-  if type "rvm-prompt" > /dev/null
-    set ruby_version (rvm-prompt i v g)
-  else if type "rbenv" > /dev/null
-    set ruby_version (rbenv version-name)
-  else
-    set ruby_version "system"
-  end
-
-  echo -n (set_color red) ‹$ruby_version› (set_color normal)
-end
-
-function fish_prompt
-  echo -n (set_color white)"╭─"(set_color normal)
-  __user_host
-  __current_path
-  __ruby_version
-  __git_status
-  echo -e ''
-  echo (set_color white)"╰─"(set_color --bold white)"\$ "(set_color normal)
-end
-
-function fish_right_prompt
-  set -l st $status
-
-  if [ $st != 0 ];
-    echo (set_color red) ↵ $st(set_color normal)
-  end
-end