[SAoC] "Improving DMD as a Library" project thread

[Mihaela Chirea]

Hello!

During the first week of working on this project I received 
multiple suggestions regarding other possible tasks that could 
better benefit the community. I started working on them from the 
second week but never clearly changed the milestones.

So, based mostly on Jacob Carlborg's suggestions[1], here are the 
new plans:

Milestone 2:
- Add the start location to the AST nodes that lack this 
information
- Bring all the dmd as a library features already existing in the 
compiler under DMDLIB
- Add the token size
- Add the end location to all nodes

Some of the issues I would like to tackle during the next 
milestones are:
- Add the possibility of analyzing source code that is only in 
memory
- Reduce the global state
- Don't generate TypeInfo when not needed (as suggested here[2])

So far, I didn't get the chance to study these last topics in 
detail and I would appreciate any advice or opinions on how to 
start working on these tasks.

[1] https://github.com/dlang/dmd/pull/11788#issuecomment-698186023
[2] 
https://forum.dlang.org/post/iopxhnudlrgiqwjxzihe@forum.dlang.org