Use excludeFilter when generating template files

This ignores editor backup files and the like. Intended
to fix #1884.

Added a hidden file to one of the scripted tests, so this
test now fails without using excludeFilters.
Adapt documentation project to API change of ScalaTemplates class

I wanted to solve this by adding a default parameter to ScalaTemplates
but since ScalaTemplates is a val and not a def, it doesn't seem possible.
Merge pull request #1892 from havocp/wip/havocp-exclude-filter-2

Use excludeFilter when generating template files