Some more minor improvements

In the past few days I've pushed a number of minor fixes/improvements out to improve gameplay.

• "Actions List" in-game will now render to the full width of the container
• "Context Menu" in-game will render items larger and now includes a "help" button
• Updated more of the tile modifiers to render using 2d assets
• Resolved a bug that would cause the UI to refelct incorrect gold/science values
• Roads now render using different textures based on the type of tile they are on
• No longer re-render entire tiles any time something changes, only update the required segments
• Single-player configuration screen now allows you to customise the names and colours assigned to each player
• Units will now flip to face the direction they are moving in