Testsuite: improve decoupling of check-matlab and check-octave rules
Do not run the Octave testsuite when --disable-octave is given
Reenable test for block with stack_solve_algo=3

Closes #407
Added algorithm section as a macro in the manual.
Added algorithms section as a macro in the manual.
Added a description of the MCMC diagnostics with a reference to Brooks and Gelman (1998).