Update 0.4.13 - Creative mode

Creative mode has been added to the demo! Currently the creative mode within a zone is unlockable as a reward by finishing all the objectives.

Once objectives are done, a button in the lower left corner can be used to activate creative mode: no restrictions on building and plant placement, quasi infinite resources, no more quests, goals or other events interfering with zen creativity.

Changelist for current update:

• Creative mode and its related gameplay and UI changes
• Things can be placed by holding down the mouse button instead of clicking one by one
• Tweaks made to weed generation and bug spawn frequency
• Removed obsolete map size selection from restart modal window