Various code clean-ups.

Made diagnostic messages a bit less 'scary'.

Fixed a segfault when using a malformed -B option.

New feature (for Toshiba): now wmpower tries to use acpi to set lcd brightness; if this fails it tries using hardware calls. This should work for newer Toshibas, where the hardware method fails.

New feature (for Toshiba): you can now adjust lcd brightness using your mouse wheel, step by step. Notice: right now, this works only for ACPI calls.