Add DefaultDarkModern Julia UDL and refresh keyword list

[abcdvvvv]

• Adds a new dark Julia UDL variant
• Updates the Base function keyword list (Keywords4)
  • tryparse_internal, bin, oct, dec, hex
  • _prevpow2, _nextpow2, ndigits0zpb
  • hastypemax, hash_integer, top_set_bit, unsafe_takestring

[oxinabox]

I am not sure if it makes sense to include things that are not part of the public API -- there are so many intenal methods in Base and stdlibs

[abcdvvvv]

This depends on whether you want to highlight only the public API or all functions.
I originally intended to highlight all functions, but to keep the keyword list concise and since enumerating all functions would be too heavy a task, it can be reverted.

[oxinabox]

You can get a list of all public functions in Base with names(Base) in the julia REPL,
and all public + private with names(Base, all=true)