Is there any place where i can check current status and plans for -preview flags?

[Dmytro Katyukha]

Hi all!

I would like to know current status and future plans for compiler 
preview flags like `-preview=in` and `-preview=dip1000`.
So, if have following questions:
- Is there any place where i could info about current status and 
future plans on these flags?
- What is the current status of these flags?
- When it is planned to enable them by default?
- Is there any description about what have to be done to make 
this flags enabled by default?
- What if i would like to create some lib that rely on these 
flags: is it ok, if i enable these flags for that lib by default?


The reason i am askin, is because part of standard library is 
@safe only if compiled with `-preview=dip1000` flag. For example, 
[std.file.dirEntries](https://dlang.org/phobos/std_file.html#dirEntries) function is safe only when dip1000 preview switch enabled, otherwise it is system.