Submodule Engine updated

Submodule Engine:
    > ad1d66d - 1) added fix so that zip file will not be considered if using development directory
    > 072fb4a - 1) cosmetic changes
    > 40322f4 - Added gtest
    > 2ae9d19 - modified project settings
    > 850b404 - modified project settings
    > bb9f0f8 - 1) added null check