Fix tao.init design lattice file.bmad@use_line-style syntax

[ken-lauer]

Description

I should have read the manual more closely, as usual:

• tao.init file section tao_design_lattice can have files with suffixes that indicate the line to be used, allowing for reusage of the same lattice file in different universes
  For example:

   design_lattice(1)%file = "NESplitter_test.bmad@Pass9"
  

  This is equivalent to "load NESplitter_test.bmad and use, Pass9"
• Separately, surprisingly, this was the first time I've parsed a file with unnecessary double parentheses (( )) and {{}} without a delimiter inside the block
  • The parser was set to bail on this scenario, but now it just passes it through. Output formatting will clean up the duplicate.

Motivation and Context

Trying latform on a tao.init file in the wild and finding more new things about Bmad

How Has This Been Tested?

Test suite

Notes

Oops, pinged a user @suffix by accident. Blame on it on the Bmad/Tao syntax...