implement Kernel#load_dsl_file
implement Kernel#load_dsl_file

This method evals the file it is given. The interesting part of it is that it
translates errors that appear in the eval-ed code into the file/line numbers of
the eval-ed file, which makes it much better for the user.

orocos-toolchain/utilrb-ext,orocos-toolchain/utilrb-ext