simpleusb and radio tune menus: Added new options (#308)

This changes simpleusb-tune-menu and radio-tune-menu to add new
options.  This brings feature parity with other distributions
of app_rpt.

simpleusb-tune-menu enhancements:
View COS, CTCSS and PTT
Toggle RX Boost Mode (show current state)
Toggle Pre-Emphasis Mode (show current state)
Toggle De-Emphasis Mode (show current state)
Toggle PL Filter Mode (show current state)
Toggle PTT Mode (show current state)
Change Carrier From (show current option) {no, usb, usbinvert}
Change CTCSS From (show current option) {no, usb, usbinvert}
Change RX On Delay (show current option) {0 to 999}
Change TX Off Delay (show current option) {0 to 999}

radio-tune-menu enhancements:
View COS, CTCSS and PTT
Toggle RX Boost Mode (show current state)
Toggle TX Boost (show current state)
Change Carrier From (show current option) {no, usb, usbinvert, dsp, vox}
Change CTCSS From (show current option) {no, usb, usbinvert, dsp}
Change RX On Delay (show current option) {0 to 999}
Change TX Off Delay (show current option) {0 to 999}
Change RX Demodulation (show current option) {no, flat, speaker}
Change TX Pre Limiting (show current option) {0, 1}
Change TX Limiting Only (show current option) {0, 1}
Change TX Mixer A (show current option) {no, voice, tone, composite, auxvoice}
Change TX Mixer B (show current option) {no, voice, tone, composite, auxvoice}

The number of new items for radio-tune-menu exceeded the number of lines
on a normal display.  Some of the options were moved to an Options Menu.

chan_simpleusb and chan_usbradio were updated to implement these new
options.  The write option in the tune menus will update the appropriate
configuration file.  Boolean fields will now be stored as 'true' or
'false'.

This closes #302.