Fixed CMake target_include_directories scope

[evilenzo]

Fixed CMake target_include_directories

Description

Divided public and private include directories for target

Motivation and Context

Issue 59

How Has This Been Tested?

Included in my project with this simple CMakeLists.txt

cmake_minimum_required(VERSION 3.1)
project(uses_bit7z LANGUAGES CXX)

add_subdirectory(bit7z)
add_executable(uses_bit7z main.cpp)
target_link_libraries(uses_bit7z bit7z64)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.