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

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

themes/mtahmed/README.md

-## mtahmed
-
-Minimal theme.
-
-![mtahmed](https://cloud.githubusercontent.com/assets/1272018/5965709/13d07f68-a7f6-11e4-9872-7936516ba258.png)
-
-#### Left prompt
-
-- First 10 characters of hostname if `ssh`'ed
-- Current directory name (not path)
-- ─╼ (cute little unicode characters)
-
-#### Right prompt
-
-- Exit code of the previous command

themes/mtahmed/fish_prompt.fish

-# name: mtahmed
-# Left prompt:
-# - First 10 characters of hostname if ssh'ed
-# - Current directory name
-# - ─╼
-# Right prompt:
-# - Exit code of the previous command
-function fish_prompt
-  set_color $fish_color_cwd
-  if [ -n "$SSH_CONNECTION" ]
-    printf '%s | ' (hostname | head -c 10)
-  end
-  if [ "$HOME" = (pwd) ]
-    printf "~"
-  else
-    printf (basename (pwd))
-  end
-  printf " ─╼ "
-end

themes/mtahmed/fish_right_prompt.fish

-# name: mtahmed
-# Left prompt:
-# - First 10 characters of hostname if ssh'ed
-# - Current directory name
-# - ─╼
-# Right prompt:
-# - Exit code of the previous command
-function fish_right_prompt
-  set -l last_status $status
-  set_color $fish_color_cwd
-  printf $last_status
-end