Pasting raw data with several sequences into alignment

Fix the following use cases:

Use case 1:

1. Open an alignment in UGENE.
2. Copy raw data with several sequences, separated by Unix/Mac OS X new line "\n", like:

   ACGT
   AAAAA
   ACACTA
   

3. Paste the data into the alignment.
   Expected state: the sequences were added to the bottom of the alignment.
   Bug state: a single sequence, made of the concatenated parts, is added.

Use case 2:

1. Open an alignment in UGENE.
2. Copy raw data with several sequences, separated by Windows new line "\r\n".
3. Paste the data into the alignment.
   Expected state: the sequences were added to the bottom of the alignment.
   Bug state: a single sequence, made of the concatenated parts, is added.