Add msg plugin. The technicolor message printer.

 + Print messages with style and color easily. Supported styles below:

     _text_                 Bold
     __text__               Underline
     ___text___             Bold and Underline
     `$variable`            Apply @<styles> to $variables
     /directory/            Directories
     [url]                  Links
     \n                     Line Break
     \t                     Tab Space

 + Recognizes 256 different color names and special @random @light @dark @error and @success labels.
 + Included also is `msg.ask` to print a message with `msg` and wait for y/n input. Returns true on y\*.

plugins/msg/msg.ask.fish

+# Print a message with msg and wait for y/n input. Return true on y\*.
+# @params → msg.fish
+function msg.ask
+  msg $argv
+  head -n 1 | read answer
+  switch $answer
+    case y\* Y\*
+      return 0
+    case \*
+      return 1
+  end
+end