Before:
* << is left shift, not allowed to shift 1 bits out
* <<% is left shift, allowed to shift 1 bits out
* >> is right shift, allowed to shift 1 bits out
After:
* << is left shift, allowed to shift 1 bits out
* >> is right shift, allowed to shift 1 bits out
* @shlExact is left shift, not allowed to shift 1 bits out
* @shrExact is right shift, not allowed to shift 1 bits out
Closes#413
Old:
```
while (condition; expression) {}
```
New:
```
while (condition) : (expression) {}
```
This is in preparation to allow nullable and
error union types as the condition. See #357
