fixed texture size, data buffering  + -> see commit message

- changed glBufferData- and glDrawElements- calls to match specification
- changed some variables (eg vertexcount, vArrayAttribPos) to match
- not sure, but i guess the main problem atm is that
float/int/short/GLint/GLuint/GLfloat/etcetc variables are somewhat
messed up, so we need to check the init-loops and callbacks, so that
there is no int or float where any GL*** variable is expected