Merge pull request #28 from Convey-Compliance/master

Minimal changes to allow compilation in Visual Studio
Fixed #28.
Use install_name_tool to name the installed dylib.
Merge pull request #31 from glyph/osx-linking

use install_name_tool to change the library name so that executables linked against it can find it without help from DYLD_LIBRARY_PATH
Because of commit 7cd8a4fa3, libscrypt_scrypt can return EINVAL, which is 22. Passing this from libscrypt_check incorrectly returns a failure as a success.
Reported by Achim Stahlberger.
Much more effecient N calculation, and now handles N > 15 (althought you wouldn't want to with today's computers).
Credit to Achim Stahlberger <achim.stahlberger@fun.de>.
Version 1.20 bump
b64.o isn't needed to be listed independantly in Makefile
ASAN test framework. No bugs found when running it.