support -e option for client

Support `-e` option on the attach client with `rdbg -A`.
`rdbg -A -e 'p 1'` will execute `p 1` at first and user can input
debug commands on REPL.

Author: ko1

lib/debug/client.rb

@@ -173,6 +173,8 @@ def send msg
     end
 
     def connect
+      pre_commands = (CONFIG[:commands] || '').split(';;')
+
       trap(:SIGINT){
         send "pause"
       }
@@ -199,7 +201,12 @@ def connect
           prev_trap = trap(:SIGINT, 'DEFAULT')
 
           begin
-            line = readline
+            if pre_commands.empty?
+              line = readline
+            else
+              line = pre_commands.shift
+              puts "(rdbg:remote:command) #{line}"
+            end
           rescue Interrupt
             retry
           ensure