Transform foundation methods

[angelolloqui]

List of some methods that could be transformed.

On List:

• list.first --> list.firstOrNull()
• list.last --> list.lastOrNull()
• list.count --> list.size
• list.isEmpty --> list.isEmpty()
• list.index(of: a) --> list.indexOf(a)
• list.append(element) --> list.add(element)
• list.remove(at: index) --> list.removeAt(index)
• list.sorted(by: lambda) --> sortedWith(comparator = Comparator(lambda))
• list.joined(separator: joiner) --> elements. joinToString(separator = joiner)

On String:

• string.count --> string.length
• string.uppercased() --> string.toUpperCase()
• string.lowercased() --> string.toLowerCase()

[angelolloqui]

Check #14 also

[angelolloqui]

Work started with 8b94a81 but still WIP