markdown: add hook to allow additional processing of code in doc

Signed-off-by: Jean Privat <jean@pryen.org>
libhtml: add HTMLTag#save

Signed-off-by: Jean Privat <jean@pryen.org>
libhtml: escape attributes keys and values

Signed-off-by: Jean Privat <jean@pryen.org>
tool: new program nitunit.nit

Signed-off-by: Jean Privat <jean@pryen.org>
gitignore: add .nitunit

Signed-off-by: Jean Privat <jean@pryen.org>
tests: add tests for nitunit.nit

Signed-off-by: Jean Privat <jean@pryen.org>
make: add nitunit to makefiles

Signed-off-by: Jean Privat <jean@pryen.org>
lib: fix implem of Range::has_only

Signed-off-by: Jean Privat <jean@pryen.org>
lib: add some examples/unit tests

Signed-off-by: Jean Privat <jean@pryen.org>
Merge branch 'nitunit'