#40 toVhdl problem with shift_left/right

[dschoeneich]

There seems to be a Problem with the translation of the following line:

led_bit_mem.next = (1 << MB-2)

After using toVhdl() to generate a vhdl file
myhdl will translate this to:

led_bit_mem <= to_unsigned(shift_left(1, (MB - 2)), 16);

This generates a compiler error.
The problem ist that the shift_left from numeric_std needs as the first argument a signed or a unsigned type.
It doesn't work with a integerconstant.

I used v0.8