Miscellaneous small fixes (fether-electron / parity-electron)

Previously, e.g. fetchParity(w, {parityChannel: "beta"}) would set
onProgress to be undefined, rather than the default () => {}

Update README.md

Compute time drift (without nodeHealth)

Fix lint error "Redundant use of `await` on a return value."

Fix bug yarn start

Convert parity-electron to typescript

Resize electron window

Clickable label + Slow instead of Cheap

Patch placeholder to look like a placeholder

Estimate Gas for tokens too