Version 0.9.13 - polishing the UI

This version is all about polishing the user interface. I did a lot of internal testing, but I wouldn't be surprised if there are some minor bugs here and there, so feel free to report any oddities you might encounter!

• ADDED: The UI panel for main buttons now has a slider to adjust the game speed. This also means that no matter if the game is paused or not, with a quick glance you can check the chosen speed.
• ADDED: Some of the UI elements show details when clicked. There now is an option to make them display a tooltip info when hovered over.
• IMPROVED: When bartering or exchanging goods the items are now grouped by category. There is an option to show / hide item groups. And items can be sorted by name or by value.
• IMPROVED: The market dialog no more shows item values in abstract units, but compared to furs.
• IMPROVED: The game dialogs now try to adjust themselves so that they won't overlap other dialogs - unless the new dialog is a modal child of a parent dialog, then the modal is shown on top of the parent, near the button which opened the child.
• IMPROVED: The mouse cursor now changes when hovering over a clickable UI element. This is currently using the OS default cursors, and the plan is to eventually replace them with custom graphics.
• IMPROVED: It is now possible to cancel a planned task by dragging its task icon upwards, out from the planned tasks panel.
• IMPROVED: The help index is now collapsible. Minimizing the index makes the help dialog smaller, making it easier to have the help open while interacting with the rest of the UI.
• IMPROVED: When hovering over a task icon or a sub-task menu item the help window, if open, will automatically show related help entry.
• IMPROVED: Hovering the pointer over an UI item now highlights the item background if the item is clickable.
• IMPROVED: When choosing what to sow the right column now shows a lot more info about each item.
• IMPROVED: When quitting the game in windowed mode, in addition to the window size also the position is now saved. The next time the game is started the window should appear at the saved position.
• CHANGED: Task sub-options menu buttons are now stylized the same as other UI buttons.
• CHANGED: The UI panel for main button toolbar now always appears at the top-right, no matter if the log is visible or not.
• CHANGED: The map scrolling and zoom in / out speed got adjusted.
• FIXED: If a planned crafting task got cancelled because of missing materials, the UI still displayed the task as successfully completed. Now there is a message indicating the task got cancelled.
• FIXED: The NPC at the marketplace selling sheep sometimes was out of sheep when visiting the market again later in the game. This is now fixed.
• FIXED: When launching the game for the first time the chosen (or, the default) hotkey configuration got accidentally messed up. Now it works as intended.
• FIXED: Crafting arrow shafts now yields correct amount.
• FIXED: A severe warning message sometimes left the game stuck in paused state with no way to resume. This is now fixed.
• FIXED: In the main menu 'Mods -> Create a new mod' only created a partial mod template. This is now fixed, so we have a minimal GUI to create a fresh mod.
• IMPROVED: More detailed error logging when initializing the game logic fails.