termio.py:  Added support for passing whatever keyword arguments you want to the terminal emulator via a `terminal_emulator_kwargs` keyword argument that can be passed to `BaseMultiplex.__init__()`.
app_terminal.py:  Added support for specifying 'enabled_filetypes' in your 50terminal.conf to control which `FileType` class will be enabled in the terminal emulator.  By default they will 'all' be enabled but if you want to disable them all just set it to 'false' or an empty list.  You can also specify individual class names to support such as `PDFFile` or `PNGFile` in a list: `["PDFFile", "JPEGFile", "PNGFile"]`