Removed unneeded function argument

The argument 'name' in vtk_add_test_tcl was eating the first test in
the list.

Change-Id: I7cfb80ce354038f5488cb0e38d4394d3bd8d4d89
Enabled easier specification of custom test name

A custom test name can be specified by giving a name followed by a
comma before the test file name, .e.g.,

CustomTestName,TestSource.cxx

CustomTclTestName,TestSource.tcl

CustomPyTestName,TestSource.py

Support for custom test names is available in:

vtk_add_test_cxx
vtk_add_test_mpi
vtk_add_test_python
vtk_add_test_python_mpi
vtk_add_test_tcl

This way to specify a custom name is more straightforward and less
verbose than the vtk_test_prefix mechanism or custom calls to
ExternalData_add_test.

Example:

vtk_add_test_cxx(${vtk-module}CxxTests tests
  TestClass,TestClass.cxx --arg0 --arg1 --arg2
)

vtk_add_test_cxx(${vtk-module}CxxTests tests
  TestClass2,TestClass.cxx --arg3 --arg4 --arg5
)

The baseline for a test with custom name 'TestClass2' is expected to
be 'TestClass2.png'.

Note that currently, every test defined from the same source file
must be defined in a separate call to vtk_add_test_*. For example,

vtk_add_test_cxx(${vtk-module}CxxTests tests
  TestClass,TestClass.cxx --arg0 --arg1 --arg2
  TestClass2,TestClass.cxx --arg3 --arg4 --arg5
)

does not work correctly - it passes --arg0 through --arg5 to both the
TestClass and TestClass2 test instances. Instead, tests with arguments
must be specified with different calls to vtk_add_test_*.

Change-Id: I88fabc4c5eca5898e257887f3e161fd9c4ee0864
Re-enabled some tests overlooked by vtk_add_test_*

The source file suffixes were missing for some tests, which meant that
vtk_add_test_* couldn't recognize them as tests. Fixed this by adding
the missing extensions.

Change-Id: Ibf5c6bc3226e0c05588a0aa2ffc6b362066de08b
Fixed some file extensions in documentation

Change-Id: I5cf196c7364eb1b88b730ddafca1680178c3160f
Merge topic 'enhance_testing_functions' into master

75d2d4b9 Fixed some file extensions in documentation
aba95150 Re-enabled some tests overlooked by vtk_add_test_*
55c7dad6 Enabled easier specification of custom test name
15504ad8 Removed unneeded function argument