org-clock.el: fix regex to recognize indented clock tables

* #BEGIN: and #END: were expected only at the first column in some
   places.
* #BEGIN: and #END: were erroneously recognized inside normal lines in
   other instances.
* always allow whitespace after #BEGIN: and #END:, not just a single space

TINYCHANGE - This patch is in the public domain.


Achim.
-- 
+<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+

SD adaptation for Waldorf rackAttack V1.04R1:
http://Synth.Stromeko.net/Downloads.html#WaldorfSDada