pyControl

Updated version numbers and changelog for v1.8.

Hardware definition file is now deleted from board when framework is loaded. The logic for this is that the devices folder on the pyboard is cleared on load framework, to revert the board to a default state with only the core pycontrol framework code installed, and this necessitates reloading the hardware definition anyway in order to reload the device files, so it is better to delete the hardware defintion file in order to generate an informative error message what a task requireing the hardware definition is run. Also this behaviour is consistent with load_framework resetting the board to a default state.