#365 - changing GSObject and HSM parameters on the fly

This pull request includes some work by Mike on #343 and by me on #365 to make it possible to change some of the GSObject and HSM "magic numbers" on the fly, rather than having to change hard-coded values and recompile each time.  These changes should facilitate some of the investigations on various issues like #343, #355, #168, #384, etc.

In order to make this work, there are two new classes (GSParams and HSMParams) that set the magic numbers.  These are passed in for example to constructors for GSObjects (in the case of GSParams) or to the moments/shape measurement routines (for HSMParams) if the user desires anything other than the defaults.

Another change from Mike's work on #343 that is included in this pull request is a fix to an issue that was causing drawShoot to use too much memory.