Add support for #-style comments

[thekid]

Before, these yielded a syntax error.

[thekid]

Comments are not retained inside the emitted code, so this may become a source of confusion if people use XP-style annotations (e.g. #[@test]) instead of the Hacklang-inspired <<test>>). Previously, there was at least a syntax error, so people would notice.

Handling this could be done by:

• ...storing them inside a doc comment (and extending XP reflection to support this), which would require new XP7, XP8 and XP9 releases to retain BC
• ...reparsing them into << ... >>-format, which is a bit tricky because of parameter annotations, which exist inside as function-level comments as @$param: annotation. ✅
• ...raising a parse error with a dedicated message
• ...retaining these comments and emitting them inside the generated source code

[thekid]

Performance

Before:

$ XP_RT=7.4 xp test src/test/php/
# ...
♥: 577/577 run (0 skipped), 577 succeeded, 0 failed
Memory used: 7818.67 kB (7876.94 kB peak)
Time taken: 0.226 seconds

After:

$ XP_RT=7.4 xp test src/test/php/
# ...
♥: 592/592 run (0 skipped), 592 succeeded, 0 failed
Memory used: 7965.44 kB (8023.70 kB peak)
Time taken: 0.228 seconds

Code

Before:

$ cloc-1.82.pl src/main/
      51 text files.
      51 unique files.
      10 files ignored.

github.com/AlDanial/cloc v 1.82  T=0.20 s (251.3 files/s, 22685.6 lines/s)
-------------------------------------------------------------------------------
Language                     files          blank        comment           code
-------------------------------------------------------------------------------
PHP                             50            536            684           3293
-------------------------------------------------------------------------------
SUM:                            50            536            684           3293
-------------------------------------------------------------------------------

After:

$ cloc-1.82.pl src/main/
      51 text files.
      51 unique files.
      10 files ignored.

github.com/AlDanial/cloc v 1.82  T=0.23 s (214.1 files/s, 19483.2 lines/s)
-------------------------------------------------------------------------------
Language                     files          blank        comment           code
-------------------------------------------------------------------------------
PHP                             50            540            684           3327
-------------------------------------------------------------------------------
SUM:                            50            540            684           3327
-------------------------------------------------------------------------------

...a difference of +34 lines

[thekid]

Handling the key/value pair syntax requires an additional 27 lines of code, and a bit of look-ahead magic. Once xp-framework/rfc#335 is fully implemented, this can be removed.