tensor - add trace_dot operation

Ignore-this: f02999647e9aef8d4c45dd0031e4f135

darcs-hash:20130924153420-3a4db-5d80e8a2f60cf0de5741cb33e7e5dae9274c4e3a
(test_linalg - fix errant print statement)

Ignore-this: 975cc1a7f3687d1491b52dcaa48b6943

darcs-hash:20130924153903-3a4db-1466d47bd2d336c4af2757594fffb0904ec10259
core - add band_e_bm_common to allow easier comparison of BandMats

Ignore-this: aad1ca77012286ce7b12a4891511d0a8

darcs-hash:20130924163431-3a4db-cbac65341b5b254b02fbe3f45375d4f174c1b4b0
(linalg - minor improvements)

Ignore-this: f5eb639049dfb5de4ad6f17f46632d03

darcs-hash:20130924180224-3a4db-4e282cad188fb8d55cf6327066b4373623fcd07f
linalg - add solve and solveh functions

Ignore-this: 84c1d68a8bbf4fc8767d00b106447b73

darcs-hash:20130924180253-3a4db-cdc03fd014afa68b250260c640f30313b1ed1710