WIP.

$ ./cmake-format -help
usage: ./cmake-format [options] [file ...]

Re-formats specified files. If no files are specified on the command-line,
reads from standard input. If -i is specified, formats files in-place;
otherwise, writes results to standard output.

options:
  -column-limit=NUMBER               Set maximum column width to NUMBER. If ReflowArguments is None, this does nothing.
  -command-case=CASE                 Letter case of command invocations. Available: lower, upper
  -continuation-indent-width=NUMBER  Indent width for line continuations.
  -indent-width=NUMBER               Use NUMBER spaces for indentation.
  -loosen-loop-constructs=always     Remove closing construct arguments in else(), endif(), etc. Always enabled.
  -max-empty-lines-to-keep=NUMBER    The maximum number of consecutive empty lines to keep.
  -reflow-arguments=ALGORITHM        Algorithm to reflow command arguments. Available: none, oneperline, binpack, heuristic
  -space-before-parens=CONDITION     When to put a space before opening parentheses. Available: always, controlstatements, never
  -i                                 Re-format files in-place.
  -q                                 Quiet mode: suppress informational messages.
  -self-test                         Run built-in test suite. This must be the first argument; all others are passed to the test runner.

TODO:

• Enforce maximum column width (moving arguments between lines + splitting up arguments to message)
  • Put one argument per line
  • Reflow arguments naively
  • Reflow breaking before boolean operators like AND
  • Figure out what a function "looks like"; does it have a run of filenames? does it start with an unquoted argument, then a keyword, then a bunch of not-uppercase stuff? is an argument a command-line option? etc.
• Do not specify content in CMake 'else()' parens
• lower-case command names in macro/function
• check CMAKE_SOURCE_DIR/CMAKE_BINARY_DIR vs PROJECT_SOURCE_DIR/PROJECT_BINARY_DIR
• sort items in SET() and LIST(APPEND) and repeated functions (like add_subdirectory, add_definitions, etc)
• variables in IF() don't always need to be a variable reference (there's some CMake policy about this, how's it actually work?)
• convert an unquoted argument with double-quotes, into a quoted argument
• use LIST(APPEND) and STRING(APPEND) instead of SET(VAR ${VAR} ...)
• no spaces between command identifiers and opening-parenthesis
• maximum blank lines in a row
• remove unneeded double quotes around variable references
• support bracket comments