C Algorithms v1.2.0

• The license has been changed to the ISC license.
• Support for compiling with gcc coverage options and running tests in
  valgrind.
• All headers now have extern "C" definitions for use in C++ programs.
• Trie free function uses a non-recursive algorithm to avoid the
  possibility of stack overflow.

Test suite:

• Framework added for testing memory allocation/free.
• Tests have been fixed to properly free any memory allocated during
  execution of the test.
• Tests have been expanded to increase the code coverage.
• A test case has been added for testing use of the program in C++
  programs.

Bugs fixed:

• Memory leak in hash table.
• Bugs with the AVL tree.
• Trie responds to out of memory scenarios correctly.