v0.3.0rc2

This release addresses the following issues:

• Added a main settings option to disable the running 'total snapshot time' since it requires extra M400 commands which can cause delays on some printers, causing print quality issues.
• For any snapshot gocde sequence, z-hop and retract now happen BEFORE the first M400 command is sent and AFTER the last, reducing delays and improving quality.
• Fixed the 'add new profile' button.
• In some cases when more than one trigger was used at the same time, the gcode of one could trigger another. This was leading to some print quality issues.
• Fixed a bug where in some rare cases the end snapshot gcode was sent out of order.
• In some cases M400s were being sent without any commands due to missing snapshot gcode sections. Now no gcode is sent to the printer in these cases.
• Sometimes the 'render end' event was occurring before the rendering task was dequeued. This caused the client to appear as though Octolapse were still rendering.
• If a print was paused, then cancelled, but Octolapse triggered a snapshot in the meanwhile (timer trigger), the cancel operation did not take effect for 600 seconds.
• Changed printer position confirmation tolerance in all of the default profiles to 0.001mm.