Separate Basilisp namespaces from python module hierarchy (#957)

[mitch-kyle]

• Fixes Can't require child namespaces #957
• Add namespace suffix for Basilisp modules. currently it's basilisp_namespace but it's not set in stone. This allows parent namespaces to require descendant namespaces.
• Create a separate namespace for __init__.lpy files that relates to the true module name.
• Modules named the same as the namespace suffix are disallowed

[mitch-kyle]

These values can be whatever. PACKAGE_NS_SUFFIX doesn't matter as much because I don't forsee much use in requiring package namespaces.

NS_MODULE_SUFFIX affects how modules are referred to from python. here are some ideas

import basilisp.core.blns as basilisp

import basilisp.core.basilisp_ns as basilisp

import basilisp.core.basilisp_namespace as basilisp

import basilisp.core.__ns__ as basilisp

import basilisp.core._ns as basilisp

import basilisp.core.basilisp_namespace as basilisp

import basilisp.core.basilisp_module as basilisp

import basilisp.core.namespace_module as basilisp

import basilisp.core._namespace as basilisp

import basilisp.core.lpy as basilisp

import basilisp.core._lpy as basilisp

import basilisp.core.lpyc as basilisp

import basilisp.core._lpyc as basilisp

import basilisp.core.basilisp_compiled as basilisp

import basilisp.core._compiled as basilisp

import basilisp.core.basilisp_generated as basilisp

import basilisp.core._generated as basilisp

import basilisp.core.__basilisp__ as basilisp