Fixing wrapped lines handling and Emoji support

[afska]

This PR migrates the fix from xtermjs/xterm.js#3718 to this library.
It also add a fix so the underlining and resulting text when calling the callback is right.

Before the fix:

(no underlining under last s)

(the last 9 from the first line is missing)

After the fix:

[rob-myers]

@afska This change to translateBufferLineToStringWithWrap was very helpful:

-    lineString += line.translateToString(true).substring(0, terminal.cols);
+    lineString += line.translateToString(true);

It fixed lineString when it contained emojis and ran over multiple rows, e.g.

ℹ️ [ corridor ]
with 11 doors

The other code broke underlining for me e.g. shifted it right by a single character for the line above.

[afska]

@rob-myers maybe have a look at xtermjs/xterm.js#5223. TL;DR using the latest official web-links plugin fixes most of these problems.