Move ruby startup code to script local function

Command-T takes about 320 ms to load on Vim startup. This is a lot
considering most other plugins takes less than 1 ms. In this pull
request I move the ruby startup code in command-t.vim to a script local
function and only call it when user uses Command-T. With this change,
command-t.vim takes less than 1 ms to load at Vim startup.

Via:

  wincent#14

plugin/command-t.vim

@@ -48,6 +48,7 @@ endfunction
 
 function s:CommandTShowBufferFinder()
   if has('ruby')
+    call s:Initialize()
     ruby $command_t.show_buffer_finder
   else
     call s:CommandTRubyWarning()
@@ -56,6 +57,7 @@ endfunction
 
 function s:CommandTShowFileFinder(arg)
   if has('ruby')
+    call s:Initialize()
     ruby $command_t.show_file_finder
   else
     call s:CommandTRubyWarning()
@@ -64,6 +66,7 @@ endfunction
 
 function s:CommandTFlush()
   if has('ruby')
+    call s:Initialize()
     ruby $command_t.flush
   else
     call s:CommandTRubyWarning()
@@ -74,6 +77,33 @@ if !has('ruby')
   finish
 endif
 
+function s:Initialize()
+ruby << EOF
+  # require Ruby files
+  begin
+    # prepare controller
+    require 'command-t/vim'
+    require 'command-t/controller'
+    $command_t = CommandT::Controller.new
+  rescue LoadError
+    load_path_modified = false
+    ::VIM::evaluate('&runtimepath').to_s.split(',').each do |path|
+      lib = "#{path}/ruby"
+      if !$LOAD_PATH.include?(lib) and File.exist?(lib)
+        $LOAD_PATH << lib
+        load_path_modified = true
+      end
+    end
+    retry if load_path_modified
+
+    # could get here if C extension was not compiled, or was compiled
+    # for the wrong architecture or Ruby version
+    require 'command-t/stub'
+    $command_t = CommandT::Stub.new
+  end
+EOF
+endfunction
+
 function CommandTHandleKey(arg)
   ruby $command_t.handle_key
 endfunction
@@ -136,29 +166,4 @@ endfunction
 
 function CommandTCursorStart()
   ruby $command_t.cursor_start
-endfunction
-
-ruby << EOF
-  # require Ruby files
-  begin
-    # prepare controller
-    require 'command-t/vim'
-    require 'command-t/controller'
-    $command_t = CommandT::Controller.new
-  rescue LoadError
-    load_path_modified = false
-    ::VIM::evaluate('&runtimepath').to_s.split(',').each do |path|
-      lib = "#{path}/ruby"
-      if !$LOAD_PATH.include?(lib) and File.exist?(lib)
-        $LOAD_PATH << lib
-        load_path_modified = true
-      end
-    end
-    retry if load_path_modified
-
-    # could get here if C extension was not compiled, or was compiled
-    # for the wrong architecture or Ruby version
-    require 'command-t/stub'
-    $command_t = CommandT::Stub.new
-  end
-EOF
+endfunction