Improve comments in checkSpace.pl to explain how to fix its warnings

    $incomment = 0;

    while (<F>) {

        ## Warn about windows-style newlines.

	#    (We insist on lines that end with a single LF character, not

	#    CR LF.)

        if (/\r/) {

            print "       CR:$fn:$.\n";

        }

        ## Warn about tabs.

	#    (We only use spaces)

        if (/\t/) {

            print "      TAB:$fn:$.\n";

        }

        ## Warn about markers that don't have a space in front of them

        ## Warn about labels that don't have a space in front of them

	#    (We indent every label at least one space)

        if (/^[a-zA-Z_][a-zA-Z_0-9]*:/) {

            print "nosplabel:$fn:$.\n";

        }

        ## Warn about trailing whitespace.

	#    (We don't allow whitespace at the end of the line; make your

	#    editor highlight it for you so you can stop adding it in.)

        if (/ +$/) {

            print "Space\@EOL:$fn:$.\n";

        }

        ## Warn about control keywords without following space.

	#    (We put a space after every 'if', 'while', 'for', 'switch', etc)

        if ($C && /\s(?:if|while|for|switch)\(/) {

            print "      KW(:$fn:$.\n";

        }

        ## Warn about #else #if instead of #elif.

        #    (We only allow #elif)

        if (($lastline =~ /^\# *else/) and ($_ =~ /^\# *if/)) {

            print " #else#if:$fn:$.\n";

        }

        ## Warn about some K&R violations

        #    (We use K&R-style C, where open braces go on the same line as

        #    the statement that introduces them.  In other words:

        #          if (a) {

        #            stuff;

        #          } else {

        #            other stuff;

        #          }

        if (/^\s+\{/ and $lastline =~ /^\s*(if|while|for|else if)/ and

	    $lastline !~ /\{$/) {

            print "non-K&R {:$fn:$.\n";

	}

        $lastline = $_;

        ## Warn about unnecessary empty lines.

        #   (Don't put an empty line before a line that contains nothing

        #   but a closing brace.)

        if ($lastnil && /^\s*}\n/) {

            print "  UnnecNL:$fn:$.\n";

        }

        ## Warn about multiple empty lines.

        #   (At most one blank line in a row.)

        if ($lastnil && /^$/) {

            print " DoubleNL:$fn:$.\n";

        } elsif (/^$/) {

        }

        ## Terminals are still 80 columns wide in my world.  I refuse to

        ## accept double-line lines.

        #   (Don't make lines wider than 80 characters, including newline.)

        if (/^.{80}/) {

            print "     Wide:$fn:$.\n";

        }

            s!"(?:[^\"]+|\\.)*"!"X"!g;

            next if /^\#/;

            ## Warn about C++-style comments.

	    #   (Use C style comments only.)

            if (m!//!) {

                #    print "       //:$fn:$.\n";

                s!//.*!!;

            }

            ## Warn about unquoted braces preceded by non-space.

	    #   (No character except a space should come before a {)

            if (/([^\s'])\{/) {

                print "       $1\{:$fn:$.\n";

            }

            #    print "     {X:$fn:$.\n";

            #}

            ## Warn about function calls with space before parens.

	    #   (Don't put a space between the name of a function and its

	    #   arguments.)

            if (/(\w+)\s\(([A-Z]*)/) {

                if ($1 ne "if" and $1 ne "while" and $1 ne "for" and

                    $1 ne "switch" and $1 ne "return" and $1 ne "int" and

                }

            }

            ## Warn about functions not declared at start of line.

	    #    (When you're declaring functions, put "static" and "const"

	    #    and the return type on one line, and the function name at

	    #    the start of a new line.)

            if ($in_func_head ||

                ($fn !~ /\.h$/ && /^[a-zA-Z0-9_]/ &&

                 ! /^(?:const |static )*(?:typedef|struct|union)[^\(]*$/ &&

            }

        }

    }

    ## Warn if the file doesn't end with a blank line.

    #    (End each file with a single blank line.)

    if (! $lastnil) {

        print "  EOL\@EOF:$fn:$.\n";

    }