typed variable declaration allows malformed syntax

#32
```
int int int
int = x
int = float
int 0 <------------- this is sick. the compiler will replace any 0 in code with the variable
int x > 5
```

should error under the following rules:

- [x] variable name can not match reserved words
- [x] the type must be followed by a valid identifier (numbers or math symbols are not allowed)
- [x] only `=` is allowed in initialization part
