* Problem: zmq_z85_decode does not validate its input
Solution: added checks for invalid characters and overflows

* Added tests, added further check for range overflow, removed (multiple) calls to strlen

* Problem: gcc fails to build
Solution: added missing include directive

* Added VS2015 test_utils_z85 project

* Fixed indentation and copyright notice

* Resolved garbage from merge

* Revert "Added VS2015 test_utils_z85 project"

This reverts commit c58b3c664c144326e77135aa1184b6f0dee11143.

* Problem: test calls zmq_z85_decode with a NULL dest
Solution: call zmq_z85_decode with a properly sized buffer

* Problem: tests for zmq_z85_* scattered over two files
Solution: merged files

* Removed reference to removed test file from CMakeLists.txt

* Problem: Missing include directive to stdint.h
Solution: Added include directive

* Define __STDC_LIMIT_MACROS before including stdint.h

* Problem: Wrong variable is checked for invalid character marker
Solution: Use correct variable