Testsuite: Move forgotten file to correct location

All testsuite stuff is now under ./tests. Consequently,
macro_pickup_tests.cmake should also be moved.
Testsuite: Update a comment
Testsuite: Also use '<>=,' as numdiff separators

This commit addresses issue #38: We have several tests in which numdiff
fails to recognize a number, because the output contains some unknown
delimiters, such as one of "<>=,".
Fix an outdated reference to fparser. Add a link.
More fixes with references that are now outdated.
Merge pull request #47 from tamiko/address_testsuite_issues

This pull_request addresses several minor issues with the testsuite:
Merge pull request #48 from bangerth/doc-fixes-5

Fix an outdated reference to fparser. Add a link.
Fix an instantiation.

The existing instantiation works, but is not in line with the actual
declaration of the function. This may or may not be the problem with
the failing tests here http://cdash.kyomu.43-1.org/viewTest.php?onlyfailed&buildid=10664
that result from a missing instantiation.
Merge pull request #49 from bangerth/fix-instantiation

Fix an instantiation.