Use markdown in readme.
Fix multiple external bug.
Added cmake module for unit testing cmake.
Be explicit about what tag is being cloned.
Ensuring expected definitions are visible.
Tightening up tests.
Added multiexport and fixed preprocessor conflict detection.
Add blurb on non-mandatory registration.
Embelish on short CPM example.
Ensure GLM has use existing version set to true.

This is the most likely use case for CPM externals.
Elaborate on USE_EXISTING_VER var.
Further explanation of USE_EXISTING_VER.
Rewording sections of 'use existing module version'.
Add a blurb on CPM externals.
Adding info regarding non-generation of targets.
Added UNID map and source directory map.

Mostly as a utility for the end user.
Fix source directory retrieval bug.
Fixed bug when using exported libs with no targets.

Added test for this case.
Lower required version of cmake.
CPM_GetSourceDir's output variable is now its first parameter.