Fixed #236: BigNumber downgrading to Number for a negative base in `pow`
Updated history
Fix matrix docs
check whether the search is a property in help function
modify test corresponding to the previous commit
Fixed #238: Unit divided by Number returning zero
Merge pull request #237 from ryanseys/patch-1

Fix matrix docs
Merge branch 'develop' of https://github.com/josdejong/mathjs into upstream-dev
Merge pull request #239 from andy0130tw/upstream-dev

check whether the search is a property in help function
Merge branch 'master' into develop
Released version 1.1.1
Basic functionality for most bitwise functions, but only minor testing. Shifts not done yet.