Change default output format to tif

[Benjamin Jakimow]

By now, the default binary output format is ENVI *.bsq + *.hdr. While ENVI binary images can be opened by QGIS explicitly, they are not shown well e.g. in the QGIS Browser.

In consequence, it is not possible to quickly open single FORCE4QGIS binary outputs, e.g. by drag and dropping them on the QGIS map canvas. (This means, the QGIS plugin FORCE4QGIS produces images which are not supported by QGIS very well)

In addition, the ENVI format might be unsuited for follow-up processing step. I therefore recommend to allow users to select the output format as well, e.g. to choose the much more common tiff format.

[Andreas Janz]

I will add a combobox for selecting the format [*.tif, *.bsq, *.vrt], with *.tif as default.

[Andreas Janz]

allow format selection in GUI; support VRT output (resolves #14, #16)

→ <<cset 8b22bd9e1e5e>>