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Fix string test for so that it works for int16
Save mirb history when readline enabled
Use env[USERPROFILE] for Windows
Changed use of MRB_INT_MAX to MRB_INT_MAX-1
Merge pull request #1391 from carsonmcdonald/fixfallbackarraysize

Changed use of MRB_INT_MAX to MRB_INT_MAX-1
Merge pull request #1389 from carsonmcdonald/stringtestfix

Fix string test for so that it works for int16
Merge pull request #1390 from kyab/mirb_history

Save mirb history when readline enabled
Merge pull request #1382 from suzukaze/add-comments

Add comments in irep.h