overhaul CONTRIBUTING.md and TODO.md

CONTRIBUTING.md is now exclusively a tutorial on how to contribute to scrot,
though it avoids duplicating the build instructions and how to acqure the
dependencies by pointing to README.md and .cirrus.yml.
I didn't move the build instructions to CONTRIBUTING.md because they're also
meant for package maintainers and savvy users.

The CONTRIBUTING.md section about looking for bug reports downstream was moved
entirely to TODO.md.

I've also added a new section to TODO.md about changing the existing code to
the new style.

CONTRIBUTING.md

@@ -1,30 +1,40 @@
-## HOW TO CONTRIBUTE TO SCROT DEVELOPMENT
+# CONTRIBUTING TO SCROT DEVELOPMENT
 
-scrot is available at https://github.com/resurrecting-open-source-projects/scrot
+#### Changes are to be sent as [pull requests on GitHub](https://github.com/resurrecting-open-source-projects/scrot/pulls).
 
-If you are interested in contribute to scrot development, please, follow
-the following steps:
+## Setting up the development machine
 
-1. Send a patch that fix an issue or that implement a new feature.
-   Alternatively, you can do a 'pull request'[1] in GitHub.
+scrot aims to build with no modifications on all the free unix systems. The
+master branch is also kept in working order at all times.  Our builds are tested
+all the way back to [Debian oldstable](https://wiki.debian.org/DebianOldStable),
+so a scrot developer shouldn't need to build the latest git versions of the
+dependencies to start hacking.
 
-   [1] https://help.github.com/articles/about-pull-requests
+You will want to install the dependencies listed in the `Building` section of
+[README.md](README.md). Look for the text `install_script` in the
+[.cirrus.yml](.cirrus.yml) CI definitions for example package manager
+invocations on many operating systems.
 
-2. Send a patch performing one of the tasks listed at [TODO.md](TODO.md)
+## Style
 
-3. Ask for join to the scrot project in GitHub, if you want to work
-   officially. Note that this second step is not compulsory. However,
-   to accept you in project, is needed a minimum previous collaboration.
+scrot is primarily written in C99 with
+[POSIX 2008](https://pubs.opengroup.org/onlinepubs/9699919799.2008edition/)
+extensions. You're also free to make use of any documented function from our
+libraries. Make sure to use
+[libbsd functions](https://manpages.debian.org/unstable/libbsd-dev/libbsd.7.en.html)
+where they're safer, cleaner or more convenient.
 
+scrot follows
+[WebKit's code style guidelines](https://webkit.org/code-style-guidelines/)
+with additional restrictions:
+- No explicit casts.
+- Use the identifier and not the type as the argument to the `sizeof` operator.
 
-To find issues and bugs to fix, you can check these addresses:
+When in doubt, make use of the `clang-format` source code formatter-it comes
+with the WebKit style by default.
 
-   - https://github.com/resurrecting-open-source-projects/scrot
-   - https://bugs.debian.org/cgi-bin/pkgreport.cgi?dist=unstable;package=scrot
-   - https://bugs.launchpad.net/ubuntu/+source/scrot/+bugs
-   - https://apps.fedoraproject.org/packages/scrot/bugs
-   - https://bugs.gentoo.org/buglist.cgi?quicksearch=scrot
+## Low-hanging fruit
 
-If you want to join, please make a contact.
+Ongoing tasks will be written to [TODO.md](TODO.md).
 
-  -- Eriberto, Tue, 12 Feb 2019 22:50:53 -0200.
+Regular contributors can ask to join the scrot project on GitHub.

TODO.md

@@ -1,8 +1,17 @@
 # TODO
 
-#### The bullet lists in this page include describe efforts in the scrot project.
+#### The lists in this page summarize current efforts in the scrot project.
 
-## Integrate [libbsd](https://libbsd.freedesktop.org/wiki/) ##
+## Fix bugs
+
+Look for any bugs reported downstream or in our github issues and fix them:
+- https://github.com/resurrecting-open-source-projects/scrot/issues
+- https://bugs.debian.org/cgi-bin/pkgreport.cgi?dist=unstable;package=scrot
+- https://bugs.launchpad.net/ubuntu/+source/scrot/+bugs
+- https://apps.fedoraproject.org/packages/scrot/bugs
+- https://bugs.gentoo.org/buglist.cgi?quicksearch=scrot
+
+## Integrate [libbsd](https://libbsd.freedesktop.org/wiki/)
 
 The BSD systems provide nonstandard C functions; many of the functions remove
 the need for some boilerplate code, and provide safer or easier to use APIs
@@ -21,3 +30,25 @@ The following libbsd integration efforts are in progress:
 - Replace error exits with the err() family of functions.
 - Replace local implementations of data structures with the sys/queue.h API.
 - Find places where other BSD functions can serve scrot well.
+
+## Comply with WebKit style
+We're currently in the process of complying with the new obligatory C style
+described in [CONTRIBUTING.md](CONTRIBUTING.md).
+
+The following files are yet to be converted:
+- src/imlib.c
+- src/main.c
+- src/note.c
+- src/options.c
+- src/scrot_selection.c
+- src/selection_classic.c
+- src/selection_edge.c
+- src/slist.c
+- src/note.h
+- src/options.h
+- src/scrot.h
+- src/scrot_selection.h
+- src/selection_classic.h
+- src/selection_edge.h
+- src/slist.h
+- src/structs.h