Various updates to bashrc
Various updates to bashrc

- Have prompt update the tab/window title
- Added `screen` function, which wraps the `screen` command to make it easier for my use:
  - Running just `screen` will connect to the named screen (or the default if none given)
    if it exists, otherwise create it.
  - Enable scroll back (ie: mouse scrolling); this only works when the screen is first
    created. Connecting to an existing screen does not let this work.
  - Can call `screen ls` to list existing screens.
- `dmesg` alias that uses useful timestamps.
JasonTarka/linux-config