Merge pull request #53 from mknoszlig/master

Problem: can't freely specify additional model parameters in project.xml
Problem: resolve_dependency always warns for custom 'use' in project
Solution: only warn if the required properties are not defined
Incidental: Use "template 0" in zproject_projects.gsl for easier editing
Problem: no newline at end of file
Solution: add newline
Problem: Too difficult to keep warning headers consistent.
Solution: Reference a variable which holds the warning header string
Problem: No builtin way to valgrind or gdb
Solution: Add 'make memcheck' and 'make debug' to automake
Problem: `make memcheck` gives exit code 0 even on failure
Solution: use `--error-exitcode=1` to fail with nonzero exit status
Problem: `make memcheck` and `make debug` do not trigger rebuild
Solution: add automake dependency on selftest libtool wrapper
Problem: Default ci_build.sh does not include memcheck
Solution: Add make memcheck to ci_build.sh
Problem: Library description in pc.in discards formatting
Solution: Don't mess with formatting of description
Whitespace fixes
Merge pull request #54 from jemc/custom_use

Problem: resolve_dependency always warns for custom 'use' in project
Merge pull request #55 from jemc/header_fix

Problem: No builtin way to valgrind or gdb
Problem: warning header interpolations in android helper taken literally
Solution: move headers outside of gsl literal
Merge pull request #56 from jemc/master

Problem: warning header interpolations in android helper taken literally
Problem: truncates example code at first '@' character

Solution: correctly end only on @discuss or @end tags.
Merge pull request #57 from hintjens/master

Problem: truncates example code at first '@' character
Problem: project needs way to assert dependency version
Solution: (autotools only) use PKG_CHECK_MODULES to assert on minimum
required version of a library.
Merge pull request #59 from sappo/master

Problem: project needs way to assert dependency version
Add documentation of script attribute, param elements.