Implement some methods for NSAttributedString and NSMutableAttributedString

[eyeplum]

This pull request contains the following NSAttributedString and NSMutableAttributedString method implementations:

NSAttributedString

• attributesAtIndex(_ location: Int, longestEffectiveRange range: NSRangePointer, inRange rangeLimit: NSRange) -> [String : AnyObject]
• attribute(_ attrName: String, atIndex location: Int, longestEffectiveRange range: NSRangePointer, inRange rangeLimit: NSRange) -> AnyObject?

NSMutableAttributedString

• init(string str: String)
• mutableString: NSMutableString
• addAttribute(_ name: String, value: AnyObject, range: NSRange)

[parkera]

@swift-ci please test

[parkera]

Neat

[eyeplum]

It seems that some unrelated tests were failing:

Test Case 'TestNSNumber.test_NumberWithBool' started at 00:50:58.936
TestFoundation/TestNSNumber.swift:43: error: TestNSNumber.test_NumberWithBool : XCTAssertEqual failed: ("Optional(-1)") is not equal to ("Optional(1)") - 
TestFoundation/TestNSNumber.swift:44: error: TestNSNumber.test_NumberWithBool : XCTAssertEqual failed: ("Optional(255)") is not equal to ("Optional(1)") - 
TestFoundation/TestNSNumber.swift:45: error: TestNSNumber.test_NumberWithBool : XCTAssertEqual failed: ("Optional(255)") is not equal to ("Optional(1)") - 
TestFoundation/TestNSNumber.swift:46: error: TestNSNumber.test_NumberWithBool : XCTAssertEqual failed: ("Optional(255)") is not equal to ("Optional(1)") - 
TestFoundation/TestNSNumber.swift:47: error: TestNSNumber.test_NumberWithBool : XCTAssertEqual failed: ("Optional(255)") is not equal to ("Optional(1)") - 
TestFoundation/TestNSNumber.swift:48: error: TestNSNumber.test_NumberWithBool : XCTAssertEqual failed: ("Optional(255)") is not equal to ("Optional(1)") - 
TestFoundation/TestNSNumber.swift:49: error: TestNSNumber.test_NumberWithBool : XCTAssertEqual failed: ("Optional(255)") is not equal to ("Optional(1)") - 
TestFoundation/TestNSNumber.swift:50: error: TestNSNumber.test_NumberWithBool : XCTAssertEqual failed: ("Optional(255)") is not equal to ("Optional(1)") - 
TestFoundation/TestNSNumber.swift:52: error: TestNSNumber.test_NumberWithBool : XCTAssertEqual failed: ("Optional(255.0)") is not equal to ("Optional(1.0)") - 
TestFoundation/TestNSNumber.swift:53: error: TestNSNumber.test_NumberWithBool : XCTAssertEqual failed: ("Optional(255.0)") is not equal to ("Optional(1.0)") - 
Test Case 'TestNSNumber.test_NumberWithBool' failed (0.001 seconds).

TestFoundation/TestNSJSONSerialization.swift:693: error: TestNSJSONSerialization.test_serialize_number : XCTAssertEqual failed: ("Optional("[0,-1]")") is not equal to ("Optional("[0,1]")") - 

[eyeplum]

Rebased to master and squashed the commits.

[eyeplum]

Hello, @parkera any update on this? Thanks.

[parkera]

@swift-ci please test