Clever output

[nohwnd]

Adds improved output, that expands $true, $false, $null, , collections dates and so on, to make the results of assertions, and test case expansions much easier to read.

Describing new assertion output
  [-] strings now have single quotes like 'this' 63ms
    Expected strings to be the same, but they were different.
    String lengths are both 4.
    Strings differ at index 0.
    Expected: ' abc'
    But was:  'abc '
    -----------^
    5:         'abc ' | Should -Be " abc"
  [-] empty string and null became <empty> and $null 36ms
    Expected <empty>, but got $null.
    9:         $null | Should -Be ''
  [-] numbers have nothing around them 30ms
    Expected 0, but got 1.
    13:         1 | Should -Be 0
  [-] decimals and doubles use point 0.1 45ms
    Expected 0, but got 0.1.
    17:         0.1 | Should -Be 0
  [-] booleans are written as $true and $false 71ms
    Expected $false, but got $true.
    21:         $true | Should -Be $false
  [-] dates are expanded to include ticks 83ms
    Expected 0001-01-01T00:00:00.0000000, but got 2018-02-20T18:39:15.7773648+01:00.
    25:         (Get-Date) | Should -Be ([datetime]::MinValue)
  [-] collections are wrapped in @() 49ms
    Expected an empty collection, but got collection with size 3 @(1, 2, 3).

Fix #944
Fix #631