Update LotuS2 wrapper to 2.28.1

Add check that the DB directory is present, due to the changes
introduced in bioconda/bioconda-recipes#41675 .

Update test data.

.tt_biocontainer_skip

@@ -1 +1,2 @@
 tools/ete
+tools/lotus2

tools/lotus2/lotus2.xml

@@ -1,7 +1,7 @@
-<tool id="lotus2" name="LotuS2" version="@VERSION@+galaxy2" profile="20.09">
+<tool id="lotus2" name="LotuS2" version="@VERSION@+galaxy0" profile="20.09">
     <description>fast OTU processing pipeline</description>
     <macros>
-        <token name="@VERSION@">2.23</token>
+        <token name="@VERSION@">2.28.1</token>
         <xml name="refDB_macro" token_ref_fasta_formats="fasta,fasta.gz">
             <conditional name="refDB_cond">
                 <param argument="-refDB" type="select" label="Taxonomy reference database">
@@ -39,8 +39,18 @@
     </requirements>
     <version_command>lotus2 --version</version_command>
     <command detect_errors="exit_code"><![CDATA[
-#import os.path
 #import re
+
+LOTUS2_DIR=\$(dirname "\$(realpath "\$(which lotus2)")") &&
+if [ ! -e "\$LOTUS2_DIR/DB" ]; then
+    {
+        echo "LotuS2 databases missing in \$LOTUS2_DIR, these needs to be installed with:" &&
+        echo "perl autoInstall.pl -condaDBinstall" &&
+        echo "We currently recommend to use a conda environment instead of a biocontainer to prevent this problem.";
+    } >&2 &&
+    exit 1;
+fi &&
+
 #def symlink_basename($f, strip_ext=False):
     #set $fn = re.sub('[^\w\-_.]', '_', $f.name)
     #if strip_ext: