Add types and functions for Packed Storage (BLAS & LAPACK)

- Type `'n Slap.Size.packed' and functions `Slap.Size.{packed,unpacked}'
  for representation of Packed Storage size
- Functions `Slap.Mat.{packed,unpacked}' and `Slap.[SDCZ].Mat.{packed,unpacked}'
  to pack and unpack triangular matrices
Add tpmv and tpsv (BLAS-2 routines)
Add ppsv and spsv (LAPACK routines)
Fix bugs in tpmv and tpsv (assertion failure)
Add a new example for trsv and tpsv
Merge branch 'packed-storage'
Merge branch 'master' of https://github.com/akabe/slap
Add types and operations for band storage
Add {un}?{ge,sy}band_dyn to Slap.Mat and Slap.[SDCZ].Mat
Add gbmv (BLAS-2 routine)
Add sbmv (BLAS-2 routine)
Add tests for geband_dyn and ungeband
Add new examples for gemv, gbmv, symv and sbmv