bugfix/issue-136-mask-drawing-order-part1

Partially addresses issue #136 after some preparation.

• Concerning commit helixhorned/eduke32@d92e53f9:
  • I want to expose my new email address only to members registered with this GitLab instance, but so far haven't found a way how.
• I use Clang++ of LLVM 15 from DEB on Ubuntu 22.04; some modifications to Common.mak are needed (not committed):
  • LLD remains at 0
  • # see if we can use -Og -> commented out
  • COMMONFLAGS += -stdlib=libc++
• The MR starts off by addressing warnings from Clang's Undefined Behavior Sanitizer
• Next and whenever needed, some refactoring, e.g. in preparation of addressing the issue in question
• Drop NEW_MAP_FORMAT (commits helixhorned/eduke32@767482d3 and helixhorned/eduke32@65ba50fe)
• Fix "search for named tile" [S] in the tile selection view (commit helixhorned/eduke32@361b0d9d)
• The main part: more precise rendering of certain cases of maskwall/sprite intersections.
  • see commit helixhorned/eduke32@99bd7791 for more detail
  • commit helixhorned/eduke32@9f3f54ad adds a manual test case mask_drawing_order.map
  • • PK: write accompanying explanation in the linked issue

---

I wanted to show the difference before/after here, but this is what I get when I drag-and-drop a screenshot .png from my file manager: (...)

Before:

After:

---

For your information:

source/sw/src/console.cpp:1154:5: warning: suspicious concatenation of string literals in an array initialization;
did you mean to separate the elements with a comma? [-Wstring-concatenation]
    "WPN_RING","WPN_ROCKET",
    ^

(The preceding line reads

    "WPN_HOTHEAD","WPN_NAPALM"

-- resulting a concatenation "WPN_NAPALMWPN_RING".)