change anyconfig.mergeabledict.ST_REPLACE from 0 to 1 and shift value of other ST_* also to avoid if ST_REPLACE was interpreted as False
fix a bug that 'replace' merge strategy (value: 0) was evaluated as False and cause an 'invalid strategy' error, and change default merging strategy
fix some test cases to follow changes in anyconfig.api
fix for some PEP8 errors and warns such like E502