Add yimmy theme

themes/yimmy/README.md

+## yimmy
+
+A simple two-line theme best displayed on a terminal configured with Solarized
+Dark colors.  Displays:
+
+     user@host cwd (branch)
+     %
+
+Characteristics:
+- Uses the fish prompt_pwd, so paths will be abbreviated
+- Git branch name will be followed by a red + if dirty
+- Indicates Git work-in-progress (gwip/gunwip) if detected
+- Tradition bourne prompt characters: $ for user, # for root
+- Prompt character is colored red if previous command had a non-zero exit
+  status

themes/yimmy/fish_prompt.fish

+function fish_prompt
+  set -l last_status $status
+  set -l normal (set_color normal)
+  set -l red (set_color red)
+  set -l cyan (set_color cyan)
+  set -l white (set_color white)
+  set -l gray (set_color -o cyan)
+  set -l green (set_color green)
+  set -l brwhite (set_color -o white)
+
+  # Color prompt char red if something failed
+  set -l pcolor $red
+  if test $last_status = 0
+    set pcolor $gray
+  end
+
+  # Traditional prompt chars
+  set -l pchar '$'
+  if test (id -u) = '0'
+    set pchar = '#'
+  end
+
+  # Determine git branch
+  set -l git_branch (begin
+    git symbolic-ref HEAD; or \
+    git rev-parse --short HEAD
+  end ^/dev/null | sed -e 's|^refs/heads/||')
+  
+  # Line 1
+  echo -n $red'┌'$cyan$USER$white'@'$cyan(hostname -s)' '$gray(prompt_pwd)$normal
+  if test -n "$git_branch"
+    echo -n ' '$green'('$git_branch
+    set -l dirty (command git status -s --ignore-submodules=dirty ^/dev/null | tail -n1)
+    if test -n "$dirty"
+      echo -n $red'+'
+    end
+    echo -n $green')'
+    # Check for gwip; does last commit log contain --wip--?
+    if begin git log -n 1 ^/dev/null | grep -qc "\-\-wip\-\-"; end
+      echo -n $brwhite' WIP!'$normal
+    end
+  end
+  echo
+
+  # Line 2
+  echo -n $red'└'$pcolor$pchar' '$normal
+end