waf: use better style for add_option() calls

Setting the "help" keyword argument may not fit in one line sometimes. This
patch adds the following convention to calls to add_option() in order to
address that issue in a better way:

    1) The "help" keyword must always be the last argument to be passed.

    2) If the help string is a literal string or a literal string with some
    operation (e.g. "%" operator) and setting the "help" keyword in the code
    doesn't fit a line (considering the limit of characters in a line), then
    the help string must be a triple-quoted string. That has the advantage of
    not having to have several "+" operations for long help strings. In that
    case, the help message must start on the next line and the closing
    triple-quotes must be on a separate line together with the closing
    parenthesis.

The requirement (1) makes it easier to make the style exception in (2)
acceptable.

Tools/ardupilotwaf/ardupilotwaf.py

@@ -366,25 +366,29 @@ def _select_programs_from_group(bld):
 
 def options(opt):
     g = opt.ap_groups['build']
+
     g.add_option('--program-group',
         action='append',
         default=[],
-        help='Select all programs that go in <PROGRAM_GROUP>/ for the ' +
-             'build. Example: `waf --program-group examples` builds all ' +
-             'examples. The special group "all" selects all programs.',
-    )
+        help='''
+Select all programs that go in <PROGRAM_GROUP>/ for the build. Example: `waf
+--program-group examples` builds all examples. The special group "all" selects
+all programs.
+''')
 
     g.add_option('--upload',
         action='store_true',
-        help='Upload applicable targets to a connected device. Not all ' +
-             'platforms may support this. Example: `waf copter --upload` ' +
-             'means "build arducopter and upload it to my board".',
-    )
+        help='''
+Upload applicable targets to a connected device. Not all platforms may support
+this. Example: `waf copter --upload` means "build arducopter and upload it to
+my board".
+''')
 
     g = opt.ap_groups['check']
+
     g.add_option('--check-verbose',
         action='store_true',
-                 help='Output all test programs')
+        help='Output all test programs.')
 
 
 def build(bld):

wscript

@@ -52,29 +52,32 @@ def options(opt):
     opt.load('ardupilotwaf')
 
     g = opt.ap_groups['configure']
+
     boards_names = boards.get_boards_names()
     g.add_option('--board',
         action='store',
         choices=boards_names,
         default='sitl',
-                   help='Target board to build, choices are %s' % boards_names)
+        help='Target board to build, choices are %s.' % boards_names)
 
     g.add_option('--no-submodule-update',
         dest='submodule_update',
         action='store_false',
         default=True,
-                 help='Don\'t update git submodules. Useful for building ' +
-                      'with submodules at specific revisions.')
+        help='''
+Don't update git submodules. Useful for building with submodules at specific
+revisions.
+''')
 
     g.add_option('--enable-benchmarks',
         action='store_true',
         default=False,
-                 help='Enable benchmarks')
+        help='Enable benchmarks.')
 
     g.add_option('--debug',
         action='store_true',
         default=False,
-                 help='Configure as debug variant')
+        help='Configure as debug variant.')
 
 def configure(cfg):
     cfg.env.BOARD = cfg.options.board