Changes to Homestead (tutorial) level (v1.07) — Keep Defending Steam update #1159754

This v1.07 update for Keep Defending changes the gameplay for the 1st level "Homestead". As this is the tutorial level for Keep Defending, and so the starting point for all new players, I've expanded its scope a little bit to introduce the management of ally units. To facilitate this I've implemented 2 additional portals (so there are now 4 overall including the player's position) and have enabled crossbow allies for this level. The hint messages displayed in Homestead have been tweaked to show when the player has (a) enough money to buy a teleport, and (b) enough money to buy an ally (crossbow). The hints also disappear automatically after a short time (before this update they remained on until the player accessed the defense interface). Note that there is a setting in the options menu where you can disable all hints permanently if you no longer wish to see them throughout the game. Hop...