tweak the visualisation of channels

[Swissnode]

In order to better compare channel sizes I suggest the following when visualising channels:

• make the sats-per-pixel scale the same for all channels
• vertically align the zero-point of all channels (where local amount meets remote amount)

Optionally:

• allow sorting by
  • channel size
  • balanced-ness (deviation per channel from 50%)
  • other criteria

[saubyk]

Sorting by channel size and balance score is already available.

We need to review your other suggestions from a UX perspective. @diogorsergio this is something we should discuss and evaluate.