This document is in debt to the contributions from several individuals. Special thanks are expressed to the following contributors (in alphabetical order of last name):
Christian Erd - Sects. 3 and 5
Kevin Galloway - Sect. 4.1
Philippe Gondoin - Sects. 3 and 5
Colin R. Haddow - Sects. 1, 3, 4.1.1, and 5.2
Mario Merri - Sects. 1, 3, 4.1.1, and 5.2
Ramon Muñoz - Sect. 4
Julian Osborne - Sect. 8
Simon R. Rosen - Sect. 8
Michal Smith - Sects. 4.1.3, 4.1.4, 4.1.5, 6.1, and 6.3
Giuseppe Vacanti - Sects. 3 and 5
Moreover, useful input and suggestions are acknowledged from M.Dahlem, N.La Palombara, D.Lumb, A.Talavera, A.Tiengo, M.Stühlinger, A.Polock, C.Gabriel, and a careful revision of the first version of the manuscript by J.Osborne.