[Tolk] Rewrite lexer, spaces are not mandatory anymore

A new lexer is noticeably faster and memory efficient
(although splitting a file to tokens is negligible in a whole pipeline).

But the purpose of rewriting lexer was not just to speed up,
but to allow writing code without spaces:
`2+2` is now 4, not a valid identifier as earlier.

The variety of symbols allowed in identifier has greatly reduced
and is now similar to other languages.

SrcLocation became 8 bytes on stack everywhere.

Command-line flags were also reworked:
- the input for Tolk compiler is only a single file now, it's parsed, and parsing continues while new #include are resolved
- flags like -A -P and so on are no more needed, actually

tolk/optimize.cpp

@@ -612,7 +612,7 @@ bool Optimizer::optimize() {
 }
 
 AsmOpConsList optimize_code_head(AsmOpConsList op_list, int mode) {
-  Optimizer opt(std::move(op_list), op_rewrite_comments, mode);
+  Optimizer opt(std::move(op_list), false, mode);
   opt.optimize();
   return opt.extract_code();
 }