Correct the directory name
Minor change to clean to avoid explicit naming of subdirectories.
Fix spelling in README.md
std::thread is movable, no need to use unique_ptr.
Only set COMPILER if it isn't set in the environment
Fix spelling of COMPILER variable in build instructions.
Merge pull request #119 from jwakely/makefile-COMPILER

Only set COMPILER if it isn't set in the environment
Merge pull request #120 from jwakely/entity-thread

std::thread is movable, no need to use unique_ptr.
Merge pull request #118 from jwakely/patch-1

Fix spelling in README.md
Merge pull request #117 from russel/russel

Minor change to clean to avoid explicit naming of subdirectories.
Merge pull request #116 from cgbarnwell/documentation

Correct the directory name
manually merged README changes from #114

Thanks @vinnievg! Closes #114