metaphlan3 and strainphlan

Adding rules for first steps of StrainPhlan and add new metaphlan rule for version 3

Closes #21 (closed)

reference

https://github.com/biobakery/MetaPhlAn/wiki/StrainPhlAn-3.0

tools/metaphlan3/metaphlan/paired/Snakefile

+__metaphlan3_exec_command = config.get('metaphlan3', {}).get('exec_command', 'metaphlan')
+__metaphlan3_modules = config.get('metaphlan3', {}).get('modules')
+__metaphlan3_input_type = config['metaphlan3'].get('input_type', 'fastq')
+__metaphlan3_options = config.get('metaphlan3', {}).get('options', "")
+__metaphlan3_threads = config.get('metaphlan3', {}).get('threads', 1)
+
+
+rule metaphlan3_paired:
+    """
+    MetaPhlAn 3 can also natively handle paired-end metagenomes (but does not use the paired-end information),
+    and, more generally, metagenomes stored in multiple files (but you need to specify the --bowtie2out parameter):
+
+    $ metaphlan metagenome_1.fastq,metagenome_2.fastq --bowtie2out metagenome.bowtie2.bz2 --nproc 5
+                    --input_type fastq > profiled_metagenome.txt
+
+    """
+    input:
+        r1 = __metaphlan3_input_r1,
+        r2 = __metaphlan3_input_r2
+    output:
+        profile = __metaphlan3_output,
+        bowtie2out = __metaphlan3_output_bowtie2out,
+        sams = __metaphlan3_output_sams
+    params:
+        exec_command = __metaphlan3_exec_command,
+        modules = __metaphlan3_modules,
+        input_type = __metaphlan3_input_type,
+        options = __metaphlan3_options
+    threads:
+        __metaphlan3_threads
+    run:
+        command = []
+        if params.modules:
+            command.append("module load {params.modules}")
+        command.append("{params.exec_command} --nproc {threads} --input_type {params.input_type} -s {output.sams} --bowtie2out {output.bowtie2out} {params.options} {input.r1},{input.r2} {output.profile}")
+        shell(" && ".join(command))