sTGCrawDataMon: output histogram and pad trigger improvements

• Histograms that need to have a binning equal to nBins = lowerLimit + upperLimit \pm 1, where lowerLimit and uppperLimit are the lower and upper end of the corresponding axis, respectively, are modified in order to have the correspoding value of the bin centered in the axis tick mark.
• Unsigned phiID is transformed to signed phiID through a method in Utils.
• Trigger relBCID vs LB per side and sector plots added in the Expert folder.

Tagging: @carquin @estel @glamprin