rawmerger: write_table_all() for direct csv output of merged table

cyt/raw_meat.pxd

@@ -33,3 +33,5 @@ cdef extern from "../lib/rawmerge.hpp":
         vector[double] get_channel(int)
         # get total merged time series
         vector[double] get_time_series()
+        # dump all channels to .csv
+        void write_table_all(const char*,char)

cyt/raw_meat.pyx

@@ -53,3 +53,6 @@ cdef class rawmerger:
 
     def get_time_series(self):
         return self.rawit.get_time_series()
+
+    def write_table_all(self, const char* csvfile, char delimiter):
+        return self.rawit.write_table_all(csvfile,delimiter)