Simplify javadoc link code

The code to generate links in javadoc is quite convoluted. There is a number of boolean flags in LinkInfo with very similar names and their interaction with the code is not very clear. The link generating code also seems to have multiple ways to do some things that could be simplified.

The purpose of this issue is not to refactor the code and change its structure or the generated documentation, but just to make it simper and clearer, paving the way for further improvements in the future.