made reduce_along_dim preserve dtype by default (as discussed in #92)
renamed dim method parameters to dimen to avoid NMatrix#dim naming confusion; added explicit call-seq blocks to mapping/reduction methods
Merge branch 'master' of git://github.com/SciRuby/nmatrix into nmatrix-reduce-type-fixes

Conflicts:
	lib/nmatrix/nmatrix.rb
NMatrix::read now refuses to read a file that does not exist. Raises an
exception instead.
Merge branch 'master' of github.com:SciRuby/nmatrix
Fixed definition of abs on complex, added real_abs, imag_abs,
piecewise_abs.
Exposed cblas asum, not tested yet
Added/exposed BLAS::cblas_nrm2, convenience functions BLAS::nrm2 and
BLAS::anum. No tests written still. Also simplified code for complex
asum calculations.
Updated readme to reflect inclusion of ASUM and NRM2
Fixed some stupid errors in asum and nrm2 (in the C code)
Added tests for nrm2 and asum
Added NVector #absolute_sum and #norm2 methods.
Merge pull request #94 from cjfuller/nmatrix-reduce-type-fixes

made reduce_along_dim preserve dtype by default (as discussed in #92)
Preparing for gem push
Version bump to 0.0.6