record.js, listview.js: Use the file array length to set clip number

Use the length of the array instead of GST_TAG_TITLE.
Number according to the number of files in the directory.
play.js: Get rid of error message for null waveform
multiple files: Implement gschema

The gschema settings were not being saved.
Closes Bug 727984 https://bugzilla.gnome.org/show_bug.cgi?id=727984