SUB macro collides with SUB=&sub;

- add SUBSCRIPT, SUPERSCRIPT like in latex.ddoc
- use SUBSCRIPT for ARGUMENTS in operatoroverloading.dd
- use ARGUMENTS instead of b1,b2..bn
Merge pull request #455 from MartinNowak/fixSUB

SUB macro collides with SUB=&sub;
Update template.dd

Inserted C++ before "template mechanics".

That is an funny twisted quote from Richard Feynman. But seriously, I would include C++ here, since D's templates are much easier to understand.
Merge pull request #456 from ralphtandetzky/patch-20

Update template.dd
Document improvements to LabelStatements
Fix link to lex.html
Fix anchors for each statements
Fix anchors more
Fix `ForeachType`

Optional `TypeCtors` now allowed
Merge pull request #458 from 9rnsr/grammar

Tweak Grammar page
Do https://github.com/D-Programming-Language/dlang.org/pull/271 in small steps
Merge pull request #459 from andralex/style.css

Do https://github.com/D-Programming-Language/dlang.org/pull/271 in small...
fix Issue 10206 - User-defined attributes not documented well in language specification

Move grammar `Property` to attribute.dd
Merge pull request #457 from yebblies/labelstatement

Document improvements to LabelStatements
Merge pull request #460 from 9rnsr/grammar

Issue 10206 - User-defined attributes not documented well in language specification
use GIT_HOME to fetch tags
separate and reuse targets to clone dmd/druntime/phobos
use hyphen instead of dot for version suffix

.${LATEST} => -${LATEST}

- This matches the versioning scheme used by others
  (github, rpm spec, ...) and simplifies interop.
only perform checkout in git repos

- check for existence of .git subdir first
use /.checkout suffix for git cloning/checkout