Added #each_row, #each_column convenience functions, doc updates, etc.
Major NVector updates: defaults to row, allows any dtype, orientation
now controlled by shape rather than a property.
NVector#to_a for list, yale. Also added #each_stored_with_index (no
spec), which is needed for list and yale #shuffle and #shuffle!, also
included in this commit (with a spec).

Added create_vector function in spec helper file.
Doc note about nd_row function needing work
Added #yale_nd_row_size. Improved #yale_a, #yale_ija, #yale_d by
allowing fetching of a single array value instead of the whole array.
Attempted to fix bug where yale matrices being multiplied may have
dissimilar dtypes (especially from the result).
Merge v0dro's #98, hopefully fixing #70
Merge branch 'master' of git://github.com/SciRuby/nmatrix into nmatrix-reduce-type-fixes

Conflicts:
	lib/nmatrix/nmatrix.rb