Fix the implementation and doc of CrossRefMap (#302)

- Handle multiple values correctly with std::multimap.
- Clarify the problematic points in the doc.
- Add some basic tests for the class.

Unification of names in heaps (#50)

Simplified implementation of bucket heaps (#50)

Port remaining heaps from SVN -r 3509 (#50)

- FibHeap
- RadixHeap
- BucketHeap
- SimpleBucketHeap

Set the version to 'hg-tip' if everything fails

Minor CMake improvements

* Use the empty ELSE(), ENDIF(), ENDMACRO(), etc. syntax since this improves
readability and requires less typing.
* Use FIND_PACKAGE() instead of INCLUDE().
* Use the value of CMAKE_COMMAND variable instead of cmake, since this works
even if cmake is not in the PATH.

Put the version string into config.h

Also make it possible to set the version using the LEMON_VERSION environment
variable, and use the hg revision as version string in case this variable is
unset.

Fix the check for the 'long long' type

Change the label of the html project in Visual Studio

Generate and install LEMONConfig.cmake

Add tools/CMakeLists.txt to the tarball

Rename documentation install folder from 'docs' to 'html'

Remove duplications from doc/CMakeLists.txt

Suppress MSVC warnings using pragmas (#295)

Add artificial addNode() function to the arc/edge set classes