Fixes custom rule regex and allow disable in code

[masters3d]

closes #717
closes #726
closes #515
Testing files:

custom_rules:
  void_as_return:
    name: "Void as Parameter"
    message: "Use Void as return type instead of ()."
    regex: "(->[ ]?\(\))"
  parenthesis_spacing:
    name: "Parenthesis Spacing"
    message: "Don't put a space inside a parenthesis."
    regex: "\(\s|\s\)"

func hey() -> () {
    return
}
/// space(  ) ( sd) (dd )
func space( ) {
    return
}

func space2( ) {
    return ( )
}

let abc: () -> () = {}

[codecov-io]

Current coverage is 89.35% (diff: 93.33%)

Merging #743 into master will increase coverage by <.01%

@@             master       #743   diff @@
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  Files            73         73          
  Lines          2442       2452    +10   
  Methods           0          0          
  Messages          0          0          
  Branches          0          0          
==========================================
+ Hits           2182       2191     +9   
- Misses          260        261     +1   
  Partials          0          0          

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[masters3d]

// swiftlint:disable void_as_return
// swiftlint:disable parenthesis_spacing

Custom rules can now be disabled in code.

[jpsim]

Thanks @masters3d! I'll push a few minor tweaks in a followup commit.