[names] __builtin__ is the Python 2 module name; IPython's run should be %run #634

Two small inaccuracies in lectures/names.md, found during native-editor review of the French edition (see QuantEcon/lecture-python-programming.fr#80, which corrected both in French). Checked at b0b0b56.

__builtin__ is the Python 2 module name. Line 336 says the built-in definitions "are stored in a module called __builtin__". Python 3.0 renamed that module builtins (What's New in Python 3.0), and import __builtin__ raises ModuleNotFoundError on current Python. Suggested: "These definitions are provided by the builtins module."

run vs %run. Line 229 says "When we run a script using IPython's run command", while the cells at lines 245 and 446 use the %run magic. Bare run only works because automagic is on by default (IPython magics); %run matches the code.

Why it is worth doing soon: until the English agrees, a translation sync that touches the adjacent bullet can revert the French builtins correction (it did in 3 of 3 simulations against the current engine). The Chinese and Persian editions carry both as written.