Segments

Moved here todo list from #26 (closed):

• fix getSerializationType the same way as in Array
• rename the method setCompressedRowLengths to setRowCapacities
• implement sparse matrices using Segments
  • implement CSR matrix and Ellpack matrix using the Segments, use existing unit tests for debugging
  • implement set/addRow using VectorView and lambda functions
• implement "Lambda matrix" - the element values are given by a lambda function
• implement constructor from initializer list to DenseMatrix
• implement method for setting elements from initializer list to sparse matrix
• implement constructor and method for setting elements from std::map similar to initializer list to sparse matrix