In-game manual

[laochailan]

Mentioned in #416.

Since the average player will not find the game manual before starting the game, maybe we can make it visible in-game.

The premium solution would be a little tutorial that starts the first time you play only. The easy way would be a simple menu entry to display the manual.

[vrpT14s]

taisei was actually one of my first touhou games, i played it recently (i liked that it was on the browser and i didn't need to download anything). for me, movement and shooting were pretty straightforward but i didn't know until much later about pressing shift to focus or that if you go to the top of the screen, you can absorb all the points in the level. i also didn't really understand that forcefield stuff you get when you have really high power.