chore(outline): apply crisp edges
fix(resize): correct resize events

This commit ensures pointer events are properly captured on the resizer.

Related to #60
feature(outline, selection): allow selection of controls

Limitations: context pad is not functional for connections

See bpmn-io/bpmn-js#121
refactor(outline): extract getConnectionBBox to util
feature(overlay): set correct positioning for overlays attached to connections

See bpmn-io/bpmn-js#121