D: Add remaining keywords, rdmd in execute command

I added the remaining keywords that weren't present before. See this:
http://dlang.org/lex.html

Additionally, I also added rdmd in execute which enables the developer to execute D program on fly.
Okay, I just realized that the bulitins in Python are highlighted through tags, so yeah, it would be better to make them highlighted using tags. I just removed those words from keywords.