Ported merge requests / issues

[moritz89]

Merge requests:

• Refactor build script to Python3 jagenjo/litegraph.js#99
• Add generic font fallbacks & prune some unused styles jagenjo/litegraph.js#294
• Fix: inner_value_change not called on slider interaction jagenjo/litegraph.js#297
• fix: declare var jagenjo/litegraph.js#334
• fix: subgraph remove output jagenjo/litegraph.js#337
• Prevent the blocks from becoming unselected when the user double-clicks or drags them.  jagenjo/litegraph.js#338
• docs: Fix a few typos jagenjo/litegraph.js#340

Issues

• Incorrect method in docstring - rebuild docs (and host on github.io?) jagenjo/litegraph.js#331
• Scrolling on MacOS cause console errors jagenjo/litegraph.js#327

[moritz89]

Changes are being merged again in the main repo, removing the need to track the manually ported changes.