Don't filter shebangs when using the 'some' comment filter

Also clarify documentation a bit more about using regexp as filter

README.md

@@ -98,8 +98,8 @@ The available options are:
                                 "@preserve". You can optionally pass one of the
                                 following arguments to this flag:
                                 - "all" to keep all comments
-                                - a valid JS regexp (needs to start with a
-                                slash) to keep only comments that match.
+                                - a valid JS RegExp like `/foo/` or `/^!/` to
+                                keep only matching comments.
                                 Note that currently not *all* comments can be
                                 kept when compression is on, because of dead
                                 code removal or cascading statements into
@@ -855,10 +855,11 @@ which we care about here are `source_map` and `comments`.
 #### Keeping comments in the output
 
 In order to keep certain comments in the output you need to pass the
-`comments` option.  Pass a RegExp, boolean or a function.  Stringified options
+`comments` option.  Pass a RegExp (as string starting and closing with `/`
+or pass a RegExp object), a boolean or a function.  Stringified options
 `all` and `some` can be passed too, where `some` behaves like it's cli
 equivalent `--comments` without passing a value. If you pass a RegExp,
-only those comments whose body matches the regexp will be kept.  Note that body
+only those comments whose body matches the RegExp will be kept.  Note that body
 means without the initial `//` or `/*`.  If you pass a function, it will be
 called for every comment in the tree and will receive two arguments: the
 node that the comment is attached to, and the comment token itself.

bin/uglifyjs

@@ -47,7 +47,7 @@ Use -c with no argument to use the default compression options.")
 By default this works like Google Closure, keeping JSDoc-style comments that contain \"@license\" or \"@preserve\". \
 You can optionally pass one of the following arguments to this flag:\n\
 - \"all\" to keep all comments\n\
-- a valid JS regexp (needs to start with a slash) to keep only comments that match.\n\
+- a valid JS RegExp like `/foo/`or `/^!/` to keep only matching comments.\n\
 \
 Note that currently not *all* comments can be kept when compression is on, \
 because of dead code removal or cascading statements into sequences.")

lib/output.js

@@ -101,6 +101,7 @@ function OutputStream(options) {
                 // multiline comment
                 return /@preserve|@license|@cc_on/i.test(text);
             }
+            return type == "comment5";
         }
     }
     else if (options.comments){ // NOTE includes "all" option

test/mocha/comment-filter.js

@@ -57,4 +57,9 @@ describe("comment filters", function() {
 
         assert.strictEqual(ast.print_to_string({comments: f}), "#!Random comment\n//test1\n/*test2*/\n");
     });
+
+    it("Should never be able to filter comment5 when using 'some' as filter", function() {
+        var ast = UglifyJS.parse("#!foo\n//foo\n/*@preserve*/\n/* please hide me */");
+        assert.strictEqual(ast.print_to_string({comments: "some"}), "#!foo\n/*@preserve*/\n");
+    });
 });