Fix display rights for sources
Fix: output_hashtbl should now work for OCaml 4.00+
Moved css to an external file to benefit from caching.

Properties using variables still need to be in the .txt file, but this should be improved.
Do not support non-UTF-8 bases any longer

Got rid of the global reference utf_8_db and some dead code.
Cleanup: Removed gwc and renamed gwc2 to gwc

Reason: there is no need to create old-format database

TODO:
- allow importing several database like the old gwc used to
- check/fix according the changelog for version 6.03:
   !!! Beware !!! This functionnality is not completly functionnal when
    using gwc2. You can not edit twice the same place. If you want to
    edit more than one time one place, you have to do a consang between
    each modifications (because it will recalculate the indexs).
Cleanup: Removed ged2gwb and renamed ged2gwb2 to ged2gwb
Removed compatibility with databases created with version < 4.10
Removed compatibility with old patches
Removed database implementation 1
Exhibited failwith with db2
Do not need an option any more
Do not need Outbase.gen_output and no_patches any more
Do not need option -i any more
Do not need just_copy any more
Removed old Mutil.decline
Removed old (unused) Date functions
Removed 'old' versions of print_mod, print_slices_menu_or_dag_page, print_anniversaries, print_statistics
Removed 'old' versions of print_relationship_dag
Field cursor and next of type string_person_index were unused
Removed Btree, replaced by Map from standard library