Make espeak options and startup behavior configurable.

FossilOrigin-Name: 153d02185cc6e0ea224ef04593383612ca2f4795e62fda3d73750c8046cf7dad

theremin/lib/theremin.rb

@@ -123,6 +123,13 @@ class Theremin
 		# Only change the note if the range finder value moves +/- this much
 		# between samples.  This helps hold pitch, and avoids "warbles".
 		setting :slew, default: 5
+
+		##
+		# Optional message to speak at startup.
+		setting :startup_message, default: nil
+
+		## ESpeak TTL options.
+		setting :espeak_flags, default: %w[ -k20 -v f5 -s 160 -a 150 ]
 	end
 
 
@@ -177,7 +184,7 @@ class Theremin
 		@threads << self.note_thread
 		@threads << self.gain_thread
 		self.led( :green )
-		self.speak "Hi.  I'm Maude."
+		self.speak( self.class.startup_message ) if self.class.startup_message
 		self.log.warn "Waiting for interaction, or ctrl-c to exit."
 		@threads.map( &:join )
 	end
@@ -268,7 +275,9 @@ class Theremin
 	## 
 	def setup_speech
 		self.log.info "Starting background espeak process."
-		cmd = %w[ espeak -k20 -v f5 -s 160 -a 150 ]
+		cmd = [ 'espeak' ]
+		cmd << self.class.espeak_flags
+		cmd.flatten!
 		@speech_io, stdout, stderr, wait_thr = Open3.popen3( *cmd )
 	end