[test][buffer] Remove unused typedefs.
Merge pull request #68 from awulkiew/fix/unused

[test][buffer] Remove unused typedefs.
[test][buffer] Remove unused typedefs.
Merge pull request #69 from awulkiew/fix/unused

[test][buffer] Remove unused typedefs.
[buffer] make buffer (miter, round) around spike possible
including unit testcase. For miters, the limit is enlarged (after
visual inspection of spike_simplex_miter)
[buffer] make constants const
[range] Fix the return type of range::erase() and add tests.