Prettier structs?

[robsmith11]

A lot of this is likely personal preference, but I thought I'd share some thoughts on what would make the printing of structs easier to read IMHO:

1. Add a space before and after the equals sign.
2. Each field on its own line.
3. Always indent fields 2 spaces (first field starts on a new line).
4. Put the closing parenthesis on a separate line.

Current output:

julia> pprint(r)
NamedTuple{(:pnl, :pnl1, :pnl2, :p1, :p2), Tuple{Float64, Float64, Float64, Params2, Params2}}(
  pnl=0.32214519260980023,
  pnl1=0.51126703754539,
  pnl2=-0.1891218449355898,
  p1=Params2(entry_decay=0.21716672940921328,
             entry_trigger_high=0.00014128907148849498,
             entry_trigger_low=0.019990643867276083,
             vol_decay=0.01, vol_trigger_high=0.000366458513092389,
             vol_trigger_low=0.000366458513092389),
  p2=Params2(entry_decay=0.032722034246227806,
             entry_trigger_high=1.1894259645369238e-5,
             entry_trigger_low=0.00014128907148849498,
             vol_decay=0.01, vol_trigger_high=8.892624233407248e-5,
             vol_trigger_low=7.026301452349746e-5),
)

Propose output:

julia> pprint(r)
NamedTuple{(:pnl, :pnl1, :pnl2, :p1, :p2), Tuple{Float64, Float64, Float64, Params2, Params2}}(
  pnl = 0.32214519260980023,
  pnl1 = 0.51126703754539,
  pnl2 = -0.1891218449355898,
  p1 = Params2(
    entry_decay = 0.21716672940921328,
    entry_trigger_high = 0.00014128907148849498,
    entry_trigger_low = 0.019990643867276083,
    vol_decay = 0.01,
    vol_trigger_high = 0.000366458513092389,
    vol_trigger_low = 0.000366458513092389
  ),
  p2 = Params2(
    entry_decay = 0.032722034246227806,
    entry_trigger_high = 1.1894259645369238e-5,
    entry_trigger_low = 0.00014128907148849498,
    vol_decay = 0.01,
    vol_trigger_high = 8.892624233407248e-5,
    vol_trigger_low = 7.026301452349746e-5
  ),
)