v3.1.5

This release only contain minor cmake improvement:

🔨 QOLM_VERBOSE if QOlm is main project 417559f
🔨 Disallow in source build 0d85845
🔨 Default build type to Release (CMAKE_BUILD_TYPE) b584c4e
🔨 Set global property USE_FOLDERS only if QOlm is main project ab92c69
🔨 Use standard CMAKE_INSTALL_INCLUDEDIR 53e1cff