Update TextRecordReader

Remove use of Deprecated org.apache.hadoop.mapred.LineRecordReader.LineReader

For every call to next, the code dives into the configuration map to see if this feature is enabled. Just look it up once and cache the value.

public int next(Writable row) throws IOException {
...
    if (HiveConf.getBoolVar(conf, HiveConf.ConfVars.HIVESCRIPTESCAPE)) {
      return HiveUtils.unescapeText((Text) row);
    }
    return bytesConsumed;
}

Other clean up.