[Enhancement] Add ``Extensions`` module

[lpeyr]

Enhancement

Add Extensions module.

Other informations

• PeyrSharp.Extensions (namespace)
  • String
    • CountWords()
    • Encrypt()
    • Decrypt()
    • SplitLines()
    • HasRepeatedChar()
    • EndsWithSamePunctuation()
  • Int
    • IsEven()
    • ToDouble()
    • GetDivisors()
  • Double
    • all conversion units that support double
  • Array (T[])
    • Append()
    • RemoveElement()