Don't unescape byte order marks in regexps

foo ? bar(x) : bar(y) ==> bar(foo ? x : y)

(x, void 0) => void x
(x, undefined) => void x

Close #374

Fix #372

bugfix #242

Make `DefaultsError` a real `Error` object

I hereby acknowledge that figure_out_scope has become a mess.

Fix #344

for now only used for keys passed to `-c` or `-b`.

`String(x + 5)` is not always the same as `x + "5"`. Overlooked that. :-(

Close #350

Fix #345

We can in fact lift sequences, but only if the operation is assignment and
the left-hand side ha...

Close #313

The "key" property was always "set" or "get", which didn't make much sense.
Now it'll be the act...

`x * (y * z)` ==> `x * y * z` -- the better place to do this is in the
compressor rather than co...

(issue #337)

Fixes #267

i.e. read `-c unsafe,unsafe-comps` as `-c unsafe=true,unsafe_comps=true`

Close #179, #326, #327

Close #335

Fix #333

Unit test to detect issue in 8d14efe for #126 that causes aggressive parenthesis removal, functi...

Fix RHS concat (raised in #330)

When attempting to concat the left-side of the rhs, make sure the rhs is
a string.

Add a unit test to test to test for aggressive parenthesis removal that causes functional changes.

Fix #269

Shorten most primitives where possible. Also optimize some edge cases.

Fix #280

The `init` of the `ForStatement` is not a `BlockStatement` before it was
descended. The descend ...

Add an exit code to the test suite

By adding the exit code 1 (or any other non-zero exit code) `npm test`
will know the tests didn'...

(with it some tests break and it can generate invalid output, see issue #44)

Fix #501

Fix #280, #282

Only allow identifier start characters at the beginning of identifiers.

Without this fix, the following source:

x = {"\u200c": 42};

would incorrectly be converted ...

allows one to specify if `foo.bar` is considered to have side effects.

unlikely to help in hand-written code:

(something() ? foo : bar) == foo ==> something()

Somebody hit me with bug reports on this. :)

Refs #300

ev() should do a single thing — evaluate constant expressions. if that's
not possible, just ret...

Close #300

Follow-up to 78e98d2.

Close #298

E.g. converts:
a+'Hello'+'World'
to
a+'HelloWorld'

See http://javascript.spec.whatwg.org/#comment-syntax
https://github.com/mishoo/UglifyJS/iss...

Simplifies handling of labels (their definition/references can be easily
figured out at parse ti...

Close #286

++/x/.y

Fix #284