Reduce to nonrecursive make.
Install script changes for parallel make.
Testing travis tolerance to make -j4
Normalize install script.
Revise install script to use 'make -j1' for travis builds.
Merge pull request #67 from pmienk/develop

Recursive make is a common pattern but also [flawed](http://aegis.sourceforge.net/auug97.pdf). This will improve reliability, including allowance for parallel make.