Directed graphs, zoom animation and bug fixes

Full Changelog

Implemented enhancements:

• Allow nodes to override strokeColor #122

Fixed bugs:

• Custom onNodeClick handler not triggering on collapsible nodes #136
• 🐛 Global viewGenerator not been applied to the nodes #130

Closed issues:

• graph constantly re-rendering even when app is idle? #145
• Allow users to pass in a function in node.labelProperty #133
• Drop yarn support for development (stick to npm only) #127
• Link mouse cursor property #119
• Center graph on a specific node #102
• Links with directional arrow #88

Merged pull requests:

• Fix/right clicks #140 (danielcaldas)
• Refactor/clean link component #139 (danielcaldas)
• fix: Trigger custom click handler in collapsible nodes #137 (LonelyPrincess)
• Add Support to pass a function to node.labelProperty #135 (dgautsch)
• Support Development on Windows Machines #134 (dgautsch)
• Feature/directional graph #132 (danielcaldas)
• Global viewGenerator included in default config object #131 (LonelyPrincess)
• Remove Yarn #128 (sasalx)
• Feature/right clicking #124 (ghardin137)
• Allow nodes to override strokeColor #123 (Andras-Simon)
• fix: #119 Add mouseCursor prop to <Link> #120 (kaungmyatlwin)
• Add onClick handler to the canvas, for use in eg. unselecting nodes #113 (smilykoch)
• Focus view on a node #107 (LonelyPrincess)