[Feature] Skin engine Themes grab text from a file %ft(file, line)

allow the skin engine to read text files and return a particular line

you then can use ss on that string to allow display of strings from the file
(Playername comes to mind)

able to be used as conditional
%?ft(filename)<Found|Not Found>

if (selected) line of file is empty the tag is treated as #COMMENT

bugfix:
%t(n)%?x<text|text>
would ignore the specified timeout defaulting to 2 seconds

bugfix: cabbiev2.128x160x16.wps was missing %Sx()
for translation on 'Next Track:'

playername.txt generated at boot if it doesn't exist contents: 'Rockbox!'

Change-Id: I04ea4fd411f74c7c6e672657949aa520c2f86f95

manual/advanced_topics/main.tex

@@ -36,6 +36,13 @@ This configuration entry can only be created and edited with a text editor or
 the Main Menu Config Plugin (see \reference{ref:main_menu_config}).
 It is not possible to change this setting via the settings menu.
 
+\subsection{\label{ref:CustomisingThePlayername}Customising The Playername}
+
+Some themes (Cabbiev2) show a customizable playername in the Whats Playing Screen.
+Edit the first line of \fname{/.rockbox/playername.txt} to show your own message
+or leave an empty file to disable the feature, deleting the file will generate a new
+playername.txt file containing 'Rockbox!' next boot.
+
 \subsection{\label{ref:OpenPlugins}Open Plugin Menu Items}
 
 Rockbox allows you to choose a plugin to run for select menu options.

manual/appendix/wps_tags.tex

@@ -755,6 +755,21 @@ a horizontal progressbar which doesn't fill and draws the image
             0 is the first conditional option
 \end{description}
 
+\begin{tagmap}
+  \config{\%ft(filename [,line]} & Get a line of text from a file.\\
+\end{tagmap}
+    Use this tag to check for the existence of a file or read a line of text from a file.
+    Checking if a file exists can be done with \%?(ft(filename)<Found|NotFound>
+    similarly you can also check if a specific line exists with \%?(ft(filename, n)<Found|NotFound>
+     where n is the desired line.
+    Note: empty files or files that do not exist are ignored by the skin engine otherwise
+\begin{description}
+    \item[filename] -- filename Note: files can only be found in \fname{/.rockbox} directory or one of its children.
+            eg. \%ft(wps/file.txt) would refer to \fname{/.rockbox/wps/file.txt}
+    \item[line] -- OPTIONAL, which line to grab, defaults to the first line.
+                    Note: lines must end  with CR or LF but may not exceed 320 characters
+\end{description}
+
 \begin{tagmap}
   \config{\%(}           & The character `('\\
   \config{\%)}           & The character `)'\\