Other preprocessor directives

#fmtstr symbol fstr values...

Formats a string with values and assigns it to a symbol.
- fstr is like a normal immediate string with formatting codes.
- "values..." are the values we want to format. Two kinds of identifiers are legal: constants and symbols. Symbols are always inserted by using the \s formatting code, all others formatting codes requires a constant.
- If the body of a symbol-value starts with single quote, the quote and its counter part are removed before insertion. Otherwise we would get unwanted quotes in formatted string.
  
  Example: -> let's create a version string!
```
#define PROG_NAME 'My Program'
#define PROG_AUTH 'John Smith'
CONST PROG_VER = 10,
   PROG_REV = 1

#fmtstr VERSTR '$VER: \\s \\d.\\d \\s by \\s' \\
   PROG_NAME PROG_VER PROG_REV _DATE_ PROG_AUTH
```
  ...would result in VERSTR looking something like: '$VER: My Program 10.1 (06.06.2008) by John Smith'
  
  The "\" char can be used to continue values on next line.

#error '..error message..'

Will make compilation fail and output the error message. Can be useful with conditional compilation.

#warning '..warning message..'

Will output the warning message. Can be useful with conditional compilation.