improve code snippets for Dirichlet character
add test file for characters
replace print statements by logger.debug calls
characters pass all 9 tests
delete obsolete file DirichletCharacter
add small tests for Hecke code
Fix some urls for Dirichlet character

This is a quick fix to make things work right. I've fixed the manually
written urls in ConductorList.html and OrderList.html by adding the word
Dirichlet.
Merge branch 'master' of github.com:LMFDB/lmfdb into pascal