started porting over volume viewing gui from raingui
bits and pieces
move odim reading and writing code in to core
fix bug in XML parser (writing error)
reimplement basic scan rendering
ported colour gradients to XML
fixed bug in gradient interpolation
port cross section rendering
further porting work for gui
reimplement volume writing
fix rendering of saved images
make building GUI optional
fix build issues when using modules on flurry
ensure nodata and undetect are not modified during volume write
implement layer masking in anc_view
ensure view consistency when zooming
fix bug in xml processor for empty attributes, remove absolute gradient paths from config file
only save configuration when manually requested
implement metadata inspection window
add prompt to save modified volumes before exiting