Removal of all solvers

This MR removes all the solvers from the master branch and updates the README file with links to the new repositories of the waves solvers.

README.md

 # waves
 
 This old repository has been split into several components which now live in their own repositories:
-- fwk & tbox: see [dartflo](https://gitlab.uliege.be/am-dept/amfe)
+- fwk & tbox: see [amfe](https://gitlab.uliege.be/am-dept/amfe)
 - flow: see [dartflo](https://gitlab.uliege.be/am-dept/dartflo)
 - waves & heat: see [amfe-solvers](https://gitlab.uliege.be/am-dept/amfe-solvers)
 - katoptron: see [katoptron](https://gitlab.uliege.be/am-dept/katoptron)