Log Message:
Update to gerbv-2.1.0.  Changes from 2.0.1 include:

*  Added ability to select objects, with the option of deleting or viewing
basic properties of the objects

*  Split off the core functionality of gerbv into a library (libgerbv) to
allow developers to quickly write software using Gerber
parsing/editing/exporting/rendering functionality.  Full DOxygen
documentation has also been created to facilitate developers wishing to use
libgerbv.

*  Added export to RS274X and Excellon functionality, allowing gerbv to
translate files between formats.  The RS274X export function can also be
used to "clean" troublesome files to a more compatible format.

*  Added the ability to override the Excellon format "guessing", allowing
non-standard drill files to be correctly rendered

*  Greatly expanded the command line functionality, including the ability to
panelize boards into a single one through the command line

*  Added "Aperture usage" tab to Gerber reports.  This allows the user to
see how often each aperture is used in all visible layers of his project.

Several notable bugs were squished in release 2.1.0:

*  Fixed bug when exporting several layers to SVG/PDF/PS, which caused
corrupted output and/or crashes

*  Fixed several Windows-only problems related to parsing and rendering

*  Fixed rendering bug when using polygon objects within step and repeat
blocks

*  Improved RS-274X export output format to work with certain Gerber viewing
software