Update zh-TW translation
Handle some illegal characters in hex string

Do not throw exception when hex strings are in the wrong format

Currently pdf.js is throwing an exception for the following hex string:

`<7 0 2 15 5 2 2 2 4 3 2 4>`

The issue is that the 15 is not a valid hex character so pdf.js ends up
throwing an exception.

This diff changes the parser to process the above hex string as follow:

`70 21 55 2 24 32` (Note: the final 4 of the hex string is ignored)

replicating the behaviour of MuPDF, and doesn't throw an exception.
Merge pull request #2540 from mduan/handle-broken-hex-string

Handle broken hex string
Merge pull request #2538 from xavier114fch/zh-TW

Update zh-TW translation