introdcute OPTION_FILENAME in order to document them differently
remove gt -list
extract method
Revert "remove gt -list"

This reverts commit 55b58f2a0b18b9d43745f863ee3461bd89465045.

Conflicts:
	src/gtr.c
update libgenometools.html
extract method
document the gt-binary itself
change the gt one-liner
fix links in tool pages
add tool links
make proper list of toolboxes shown in documentation
coding style
make sure -help and -version exist in generated documentation
make output of toolbox list nicer

fix documentation for readjoiner