* data/Makefile.am, data/scim-sinhala.png: Rename from scim-canna.png
* src/scim_sinahala_imengine_factory.cpp: Disconnect reload signal in
destructor.
* src/scim_sinhala_imengine.{cpp,h}: Split some codes from
sinhala_transliterated_filter_keypress() to handle_consonant_pressed()
and handle_vowel_pressed().