Add Ai names #6

Names are read from the AiNames file. A random selection
is chosen for each session.
Add bullet obstacle and implemented factory

* Add Bullet obstacle with constructor
* Obstacle factory can now be used to make bullets
* Modify Log should now work
* Add GraphicBank for quick access to often used graphics
* Add bullet graphics
Merging
Merge branch 'master' of https://github.com/bjorfoss/XNAX1
Merging
Add constructor in Unit. Make spawn astroid function
Fix merge conflict
Merge remote-tracking branch 'origin/input'
Add level limits #18

* Add IsOutsideLevel to check if a unit has moved outside of bounds
* Add GetLevelBounds to get the bounds for the level
Merge remote-tracking branch 'origin/master' into level-limits
Fix unit constructor, checkIfInSideLevel, GraphicsBank get method
Add method to get Level instance from GameObject
Merge remote-tracking branch 'origin/input' into level-limits
created SpaceStation.cs
Fix case sensitive methodname error
Merge remote-tracking branch 'origin/master' into input
Add warning message for leaving the combat area
Tweaks to make the game run on older systems

* Switch project API from HiDef to Reach
* Make background 1024x1024 (was 1000x1000)
* Draw menu screen differently from ingame screen, since there were a lot
  of non-power of two textures there and I didn't have time for anything
  more complicated.
Change GraphicBank

* Add font support: use GetFont("fontName")
* Replace repeated calls to GetContentManager with a variable
* Make Unit debug text use the new capability
Fix SpriteFont render issue

Change the sorting mode of sprites from BackToFront to Immediate