Allow plugins to modify the core behaviour

[vaibhav-kaushal]

Hello all,

I have been trying to work on #815 and while creating plugins is a great way to get things done, I believe there can be many points where we might want to allow a plugin to alter the core behaviour, when installed.

I believe, the way to do that would be how we did it in version 2.2 - maintain a file where we list the plugins installed and use it. The way to improvise would be to create hooks within the core framework where we check if a plugin wants to be called at that point and if one is installed, a pre-defined function within the plugin could be called.

I am building something exciting on my end which might need this and can help future developers to get onboard by creating plugins according to their need!

[spekary]

This I believe is the same as #868