Move way full and relation full calls out of experimental

To clean-up old files, remove test/*experimental.log
Remove --enable-experimental from ./configure
Use the number of selected ways/relations in full calls

This is a slight optimization for queries against deleted nodes
as it avoids a select, but it is a significant improvement for
backends like pgsnapshot with no history because now no queries are
needed to check for non-existant ways
Fixed error in conversion of instances parameter.

This fixes bugs #54 and #55: If a non-numeric argument is provided
then the error message is:

  Exception: in option 'instances': invalid option value

If the option value is zero or negative, then we get:

  Exception: Number of instances must be strictly positive.

And the `bad_any_cast` exception is gone.
Merge pull request #51 from pnorman/full

Move full calls out of experimental
Merge pull request #53 from pnorman/full_not_found

Use the number of selected ways/relations in full calls