New tag %ft grab a line of text from a file

[Bilgus]

Work in progress
%ft(filename, line)
https://gerrit.rockbox.org/r/c/rockbox/+/6143

Get a line of text from a file and display it in the wps

Comments welcome

[iPodVT]

Work in progress
%ft(filename, line)
https://gerrit.rockbox.org/r/c/rockbox/+/6143

Get a line of text from a file and display it in the wps

Comments welcome

It works perfectly for me on both ipod6g and ipodvideo, for everything I tried.  I made a four line text file, and tested it for each line.  I also tried some out of bounds line numbers and they produced an empty string (at least apparently - nothing was displayed from the calls with those bad line numbers).  I also tried with and without a newline/CR for the last line and it worked properly both with and without.  I guessed that the line numbers would be zero-based and that proved to be the case.  I didn't do extensive stress testing, e.g. very long lines of text.  Please let me know of any specific such testing you'd like me to try.

I hope others will find this useful.  Although the 'player name' config setting fulfilled my need/desire to be able to cache a displayable unique name for each individual device, this text file implementation is better because now instead of having to hard code a unique config setting for each player, they can all share the same generic config file and just have their own unique text file of line delimited data, which is much easier to maintain.

Thanks very much for providing this great new feature.