Improve error message for prefech-on-indirect-access, add test (#104 on gitlab)

See merge request inducer/loopy!183

Precompute default tag mandatory

See merge request inducer/loopy!268

Ensure unpickles equally on callbacks

Closes #136

See merge request inducer/loopy!267

Reenable pypy and binary-build CI

See merge request inducer/loopy!266

No defaultdict for iname to tags

See merge request inducer/loopy!265

Merge branch 'add-local-strides-global-strides-and-var-name-to-local-mem-access-stats' into 'master'

Now counting lid strides, gid strides, and variable name in LocalMemAccessCounter. Updated tests accordingly.

See merge request inducer/loopy!263

Fix various issues with dependency cycles

See merge request inducer/loopy!264

draw_dependencies_as_unicode_arrows: Fix (never-ending) drawing of downward arrows, indicating cyclic deps