Tracking Issue for no_std

[akern40]

Just so I can keep track of a few things:

• Some issues running tests with Issues when running tests #1487
• Mainly caused by linspace only being available with feature = "std"
• See no_std for ndarray #708 for the originating issue for us
• See Float should require FloatCore rust-num/num-traits#197 for the corresponding discussion that ndarray contributors had started with num-traits