Error when compiling "Does not name a type"
Since your class MyLiquidCrystal is declared inside a namespace (MyProject), you need to use the full type name to use it outside of that namespace. In your case, you should replace:

MyLiquidCrystal lcd(8, 9, 4, 5, 6, 7);


by

MyProject::MyLiquidCrystal lcd(8, 9, 4, 5, 6, 7);


Alternatively, you could add the following line at the top of your sketch:

using namespace MyProject;


This will tell the compiler that the whole content of MyProject namespace should be imported to the global namespace, which will allow direct access to its content.