#248 Add TEMPLATE_DIR CMake variable for custom project template configuration.
Modify basis_use_package to do nothing if module dependency is BASIS.

Clearly when the basis_use_package(BASIS) command is called in basis_project_impl of a module, the BASIS package must be available already. Otherwise, these commands would not exist. Further, the top-level project already included the BASISUse.cmake file through basis_use_package called by basis_project_impl within the root CMakeLists.txt of the top-level project.
Exclude mercurial repository files as well.
Merge branch 'develop' into feature/add-template-dir-cmake-variable

Conflicts:
	data/CMakeLists.txt
Fix installation of custom project template files. (incl. CMakeLists.txt).
Change project template directory structure and default template options.
Fix configuration of sbia/1.8 project template.
Move PROJECT_TEMPLATE from root CMakeLists.txt to TEMPLATE argument of basis_project in BasisProject.cmake.

Do not use full path for TEMPLATE argument if template is part of the BASIS installation.
Merge branch 'feature/add-template-dir-cmake-variable' into develop
Merge commit '0666c27359625d7266b034f4f23303301c9d84d0' for allowing basis as a module of a basis project into develop from issue #256 https://github.com/schuhschuh/cmake-basis/issues/246
Issue #237 Correct dead links in Basis Introduction. Also improved clarity and updated outdated parts of the presentation to match the 3.0 release.