Refactor calculations according to new specs

Change much of the mathematics in flush_matrix.py to reflect changed
specs: family group removed; demulse and dyes given constant values to be
read from config file; equipment loaded from excel files; equipment passed
as a parameter into elemental factor calculations; GUI and gui_handler
altered to reflect new use cases (additional parameters needed for
specific departments).
Merge branch 'master' of https://github.com/johnsaigle/flush-tool