Create lexer for ucode

[eric-j-ason]

The ucode language is "a tiny general purpose scripting language featuring a syntax closely resembling ECMAScript". It was created for use in OpenWrt, the Linux distribution commonly used in routers and other embedded devices.

I used the JavaScript lexer as the starting point, and removed the keywords not used in ucode (and added one or two).

Questions:

• What is the difference between Keyword and KeywordReserved? The JavaScript lexer uses both, but I don't see the pattern.
• Should KeywordNamespace be used for import, as, from, and maybe export? The JavaScript lexer does not use it, but the Python one does.

[alecthomas]

In some languages, a "reserved keyword" is a keyword that cannot be used for user defined symbols in any context. Other keywords can be

[alecthomas]

Basically there's no right or wrong answer, just use your best judgement. You can be more or less specific, as required.

[alecthomas]

I'd suggest adding some tests. See the README in lexers/testdata for details.

[eric-j-ason]

I'd suggest adding some tests. See the README in lexers/testdata for details.

I will do so.