Document opDollar.
Clarify about opDollar without compile-time argument.
Fix wrong example code.
Move opDollar docs to its own section.

Expand with feedback from Kenji, Don, et al.
Added resource files needed by the ddox generated API docs.
Add necessary files and build targets to generate API docs using the dpl-docs generator.
Tweak CSS style of the new API docs.
Remove entries for deleted Phobos modules.
Remove "register" as a D keyword in the syntax highlighting script.
Improve style of get/set annotations and make anchors in headers less bold.
Add a "apidocs" target in win32.mak to generate API documentation using dpl-docs.
Add a win32 make target for HTTP serving the API documentation locally instead of generating HTML files.
Add indicators for inherited class members and the protection level of symbols.
Add newline before EOF.
Remove redundant macro definitions in std-ddox.ddoc and add an "apidocs-serve" target in posix.mak.
Let win32.mak generate the list of needed source files for the apidocs targets on the fly.

api-docs-files.txt isn't needed anymore on Windows.
Let posix.mak generate the list of needed source files for the apidocs targets on the fly and remove api-docs-files.txt.
Output DDOX based documentation to library/ instead of phobos/ to allow having both at the same time.
Remove section in style guide about comments.

We don't really follow the guidelines on comments, and some of them are
arguably outright bad (e.g. using version(none) does not play nicely
with syntax highlighting, since the code appears to be active unlike
when it's commented out). There was some agreement on this when I
brought it up in the past, but for the most part, no one even responded
to attempted discussions on it. But since we don't really follow the
comment guideliness, and they _are_ bad in at least one case, I think
that it's far better to just remove them. The only case where we even
get any dispute about comments at this point is whether ddoc comments
should use /++ +/ or /** */ and the comment guidelines don't discuss
that.
Changed `bit` to `bool`

Because of error "undefined identifier bit" we need to change `bit` to `bool`.