Packaging improvements

[Niautanor]

1. It is now possible to install the library to an arbitrary prefix by setting CMAKE_INSTALL_PREFIX and SYSTEM_INSTALL
2. The filename of the library no longer conflicts with openssl when installed. This should not have an effect when using the library as a git submodule.

Closes #271

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.29%. Comparing base (ee6d707) to head (0989519).

Additional details and impacted files

@@           Coverage Diff           @@
##              dev     #278   +/-   ##
=======================================
  Coverage   83.29%   83.29%           
=======================================
  Files          39       39           
  Lines       11049    11049           
  Branches      832      832           
=======================================
  Hits         9203     9203           
  Misses       1544     1544           
  Partials      302      302           

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[rjbrown2]

Looks good. Awaiting review from others.