Improve compilation time

[tomasz-czyzak]

Checklist

• [ ] New Extension
• [ ] New Test
• [x] Changed more than one extension, but all changes are related
• [x] Trivial change (doesn't require changelog)

Before:

3188.93ms EZSwiftExtensions/Sources/StringExtensions.swift:114:26    instance method uppercase(range:)
3139.85ms EZSwiftExtensions/Sources/StringExtensions.swift:178:26    instance method lowercase(range:)
3129.81ms EZSwiftExtensions/Sources/StringExtensions.swift:122:17    instance method uppercased(range:)
3005.32ms EZSwiftExtensions/Sources/StringExtensions.swift:186:17    instance method lowercased(range:)
639.91ms  EZSwiftExtensions/Sources/UIColorExtensions.swift:20:24    initializer init(hexString:alpha:)

After:

22.07ms   EZSwiftExtensions/Sources/StringExtensions.swift:114:26    instance method uppercase(range:)
21.70ms   EZSwiftExtensions/Sources/StringExtensions.swift:184:26    instance method lowercase(range:)
22.24ms   EZSwiftExtensions/Sources/StringExtensions.swift:125:17    instance method uppercased(range:)
21.43ms   EZSwiftExtensions/Sources/StringExtensions.swift:195:17    instance method lowercased(range:)
115.60ms  EZSwiftExtensions/Sources/UIColorExtensions.swift:20:24    initializer init(hexString:alpha:)

[tomasz-czyzak]

Build failed due to:

Xcode 10.0 cannot be installed on macOS 10.12.