Merge pull request #5 from MeraX/master

Fix of stroke width an simple despiking by MeraX
We're using the math library which should be linked with '-lm'. Probably some other library already handles this for us but explicitly adding it to the linker can't hurt.
Added MeraX's idea to add a command-line option for disabling stroke width;
Added an idea of myself;
Fix for GUI: Floating-point numbers need to be written with a dot, not a comma.
Added the ability to convert to PNG and PDF from the command-line.
A couple of memory fixes;
Fix for "old" GLib version;
Fix for PDF cut-off;
Update the TODO file to the current state of the program.
Basic color support by pressing the "new layer" multiple times.
Update to current program state.
Added the new feature to the README.
Introducing a new namespace: "high" -> For functions that combines other functions;
Added the ability to scroll the document in the GUI;
Updated the win32 target to include the high-level functions;
Fix for window resizing;
Updates for project's status.
Added a screenshot to the README.
Changed the program's title to InklingReader.
The scrollbar behavior on Windows seems to be a bit different. Removing the scrollbar policy doesn't seem to affect GNU/Linux and benefit Windows;