Create makefile

[nyxxxie]

Create a makefile for easier interfacing with spade by package managers and users. Define the following targets:

• all (AKA first target) - Builds native executable
• unix - builds frozen executable for spade
• win32 - builds frozen executable for win32
• osx - builds frozen executable for osx
• install - installs spade
• virtualenv - creates and activates virtualenv
• venv - same thing as virtualenv
• docs - builds sphinx docs
• help - displays help

See if there's a system or standard that already exists for this? Also, the packaging/install method might be subject to change between this issue and when the feature is going to be implemented, so check how install is currently done (as of 5/20/2017, dependent on #3) before implementing.