Implemented sendConfig. Switch to 8-bit wiring.

For some reason 4-bit mode/wiring didn't seem to be working for
my LCD, even when controlled from other programs. Not sure
what's going on, but I'm not dealing with it right now. 8-bit's
only drawback is uing four more pins, which I'm not worried about.

Made a few changes to remove "magic numbers" relating to 4 vs. 8
bit mode differences. As part of this, added constant ints
gpioTotal and oneLineMode to gpio_lcd.cpp.

Due to change from four to eight bit mode, sendCommand was
modified. Basically, it writes all eight bits in one go, then
pulses pin E, instead of splitting it into two chunks.