specify alignment for printing Pair in arrays

[rfourquet]

Before:

julia> [1=>22, 33=>4]
2-element Array{Pair{Int64,Int64},1}:
 1=>22
 33=>4

After:

julia> [1=>22, 33=>4]
2-element Array{Pair{Int64,Int64},1}:
  1=>22
 33=>4

[StefanKarpinski]

Looks good to me. Should we also print pairs with spaces around the =>, i.e. 1 => 2?

[rfourquet]

Should we also print pairs with spaces around the =>, i.e. 1 => 2

I at least wanted to propose this! I planned to make the non-compact form of pairs show spaces, and to not use compact printing for vectors.

[rfourquet]

The CI failures seem unrelated, but should we restart them?

[rfourquet]

I will merge by tomorrow if no-one objects; this seems to be uncontroversial.