[NTG-context] file dependencies

Hello, Here comes a little feature request: it would be nice, if context allowed us to write a file with dependency information, like a C-compiler does for the dependencies of a C-file on the included header files. The best would be, to get such dependencies directly in Makefile syntax. Example: Say you have a main context file "main.tex" that includes an environment file "../env.tex" and a figure "subdir/figure.jpg", then running context --dependencies=main.d main would create "main.pdf" and also "main.d" with this line: main.tex: ../env.tex subdir/figure.jpg -- Peter