D3.js: Remove leading zero from time format

In D3.js, all time format directives are zero-padded by default (except for %e which explicitly uses space-padding).

For example, using d3.timeFormat("%I:%M") will output 09:34.

To change the padding type, append a modifier to the directive’s %:

• 0 to use zero-padding
• _ to use space-padding
• - to disable padding altogether

Following the above example, using d3.timeFormat("%-I:%M") will yield 9:34.