v0.3.1

• Change errors/warnings to use call.=FALSE or equivalent.
• Refactor C code to reduce complexity
• Change C code to play nicely with rchk

From lotri 0.2.2 (not tagged)

• Bug fix for conditional matrices
• Now accessing $lower and $upper gives default values even if it
  wasn't specified.
• Can change the default conditional matrix to some other value like "id"
• Can add properties to matrx->lotri by as.lotri(matrix, lower=3, default="id")
• Dropped Matrix import and added lotriMat to create banded
  matrices (faster than Matrix for now included repeated matrices
  with list(matrix, rep)).
• Bug fix for default properties when both upper and lower bounds are specified