remove deprecated library/function calls

Dear Laurent,

thanks for your great `RforProteomics` package.
I have two small fixes for the `MALDIquant` example:
 1. `readBrukerFlexData` is imported by `MALDIquantForeign`, there is no need to call `library("readBrukerFlexData")`.
 2. `MALDIquant` provides its own `movingAverage` function now (since version 1.5), there is no need to define your own `simpleSmooth` function anymore.

Best wishes,

Sebastian