Modified GetSize

I needed some modifications to GetSize macro:
1) fixed the problem with >2 GB filesizes (also in Locate).
2) I wanted a practical way of getting accurate size in units other than B, for displaying it to end user. You can now specify /S=Auto and size will be returned as n,nn KB|MB|GB (if >1023 B). Also, instead of a dir as the first parameter you can pass a value representing size in bytes to have it autoconverted.