WG11 -- Add Tolerance + Change CoverGlassNo to CoverGlassNumber Fields to CoverGlass

[strambc]

Element name(s): CoverGlass

Justification for the addition (brief and compelling):
Missing CoverGlass attributes proposed by WG11

New Field name(s): __

Tolerance (Thickness tolerance)
CoverGlassNo --> CoverGlassNumber

Current Description: "This fields reports the numerical designation that describes the expected thickness of this Coverslip (e.g., #1.5) and the relative expected thickness range expressed in mm."

New Description: "
Current Description: "This field reports the numerical Grade that describes the expected thickness of this Coverslip (e.g., #1.5) and the associated relative expected thickness range expressed in mm."