Add RecordSeries::get_record and support for (my_ticks 0)

This commit introduces the `get_record` method to `RecordSeries`,
allowing for the dynamic reconstruction of a full record from its
constituent fields at a given index. This enables idiomatic access to
series data using indexing like `(my_ticks 0)`.

The `push-series` function has also been updated to correctly handle the
structure of records when pushing data into a `RecordSeries`.

examples/soa_series.myc

@@ -1,15 +1,15 @@
 ;; Output: 26.7
-;; Benchmark: 998ns
+;; Benchmark: 998ns
 ;; Benchmark-Repeat: 2047
 (do
-  (def template {:price 10.0 :volume 100})
+  (def template {:price 10.0 :volume 100 :msg "hi"})
   (def my_ticks (create-series template))
 
-  (push-series my_ticks {:price 10.5 :volume 100})
-  (push-series my_ticks {:price 11.2 :volume 200})
-  (push-series my_ticks {:price 15.5 :volume 300})
+  (push-series my_ticks {:price 10.5 :volume 100 :msg "A"})
+  (push-series my_ticks {:price 11.2 :volume 200 :msg "B"})
+  (push-series my_ticks {:price 15.5 :volume 300 :msg "C"})
 
   (def prices (.price my_ticks))
 
   (+ (prices 0) (prices 1))
-)
+)