The flag consists of the new `data/.compilation-symlinks` file, which is included in the code base (but not available in the Combodo packages).
It will be used and generated if and only if :
* we are on a dev env (`\utils::IsDevelopmentEnvironment`)
* the `symlink` PHP function exists
The flag is generated low level in the compiler (\MFCompiler::DoCompile)
In the setup, if the flag is present and all conditions are met then a new option will be displayed in the "Miscellaneous Parameters" wizard step. When unchecking/checking the flag will be updated accordingly by an ajax query.
All other compiler consumers (Designer / Hub connectors, Core Update, scripts using `RunTimeEnvironment` class) will :
* if they provide a value for the symlink option, it will be used
* otherwise the flag will be used instead, if conditions are met
