Add utils for working with endianness, more documentation, refactor CMake

Decided to update the docs, as well as adding few new features and small
refactoring.

test/CMakeLists.txt

@@ -24,7 +24,7 @@ foreach(TEST_FILENAME ${TEST_FILES})
     endif()
 
     # Enable coverage
-    if(COVERAGE)
+    if(ENABLE_COVERAGE)
         target_compile_options("${TEST_NAME}" PRIVATE -coverage)
         target_link_options("${TEST_NAME}" PRIVATE -coverage)
     endif()