The existing MatrixMarketScalar is relatively closely tied to the way
oru parser is implemented. I've moved these internals into an internal
trait and sealed the public trait.
This makes it less flexible for users for now, but gives us more freedom
to change internals in the future.
1. Several renamings
2. removed unnecessary traits
3. added support for dense matrix
4. removed unnecessary comparison when reading data line by line. (e.g.
only read header line once)
Hantao Hui
Andreas Longva