Added valgrid option for all test targets.
Fixed LCA test.
Added deletion of code coverage info.
sigma is already in csa. Removed local member.
Fixed documentation of edge().
Increase code coverage of tests and replaced

rank_bwt -> bwt.rank
Fixed typos.
Fixed iterator and increased code coverage of test
Adjusted to new API.
Renamed smaller_lex_count to lex_smaller_count
Renamed constants namespace to conf
Added string_type to simplify extract method.
Addressed issue #101
Added iterators for WTs; fixed examples.
Added difference_type.
Removed unnecessary private keyword.
Merged wt_rlmn and wt_int_rlmn. int_vector_buffer

is now used in the construction.
Added another test input.
Merge pull request #100 from simongog/tests

Tests