Update id_dist to version 0.4

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Signed-off-by: Andreas Kloeckner <inform@tiker.net>
Fix for stats.mode to work on character arrays. Closes #3814
Fix pyflakes complaints on whitespace, mark test as knownfailureif python 3 (relates to open numpy issue)
Merge pull request #3857 from pfctdayelise/master

Fix for stats.mode to work on character arrays. Closes #3814
Fix reference computation in ID rank estimation to use relative rank

Signed-off-by: Andreas Kloeckner <inform@tiker.net>
Use the 2-norm in the rank estimation test

Signed-off-by: Andreas Kloeckner <inform@tiker.net>
Fix test for matrix-free rank estimation (as recommended by Ken Ho)

Signed-off-by: Andreas Kloeckner <inform@tiker.net>
Merge pull request #3843 from inducer/upgrade-to-id-dist-0.4

Update id_dist to version 0.4