Use Irony mode for C++ autocompletion.

Irony mode provides an intelligent autocompletion based on libtooling
from the clang project.
Eliminate tooltip delay and truncate lines.

Make the user interface more responsive by eliminating the delay for the
tooltip and truncating the lines instead of wrapping them on the screen.

This also addresses an issue where both ansi-term and emacs buffer
interface attempt to wrap the same line, resulting in a double wrapping.