Make small fixes on developers' testing page.

Main problem was the OmeroPy path which was simply wrong.
Use canned styles following sbesson's suggestions.

also cleaned up some whitespace
Fix test class links, per sbesson's suggestion.
Ressurect the ArrayColumn documentation

This reverts commit 48f3a5c3bb4b1b25e1306c93a50b30a68388c39b.
Added doc for FloatArrayColumn
Add clarification that Float/Double/Long are 32/64/64 bits
Remove long from values type since it applies to multiple column types
fixed width -> fixed-width
Make further changes suggested by Helen.
Merge pull request #283 from manics/rebased/develop/tables_arraycolumns_9957-2

Tables ArrayColumn docs 9957 (rebased onto develop)
Merge pull request #280 from mtbc/fix-test-doc-dev

Make small fixes on developers' testing page. (rebase)