F103VC, F105, and F107:  Fix configuration and building of USB.  configs/viewtools-stm32f107:  Fix build for F103 and F107:  F103 has USB device; F107 has OTGFS

Viewtools netnsh configuration supports Telnet console; A framework for SD card and USB device support

Add logic to configure interrupt controller debug; Fix high priority, nested interrupt build problems

viewtool configuration will not support boad with STM32F103VC mounted; converted one stm3210e-eval configuration to use kconfig-frontends

Finishes coding of ARMv7-M high priority nested interrupt logic.  Still undocumented; still not fully tested

Remove all configuration variable documentation from configs/README.txt and Docuemntation/NuttXPortingGuidle.html.  The current NuttX configuration is documented in Kconfig files and in Documentation/NuttXSonfigVariables.html.  The older configuration variable documentation is not being maintained and, hence, is a liability