[MINOR] adjust error messages about conflicting proxies

It's not easy to report useful information to help the user quickly
fix a configuration. This patch :
  - removes the word "listener" in favor of "proxy" as it has been
    used since the beginning ;

  - ensures that the same function (hence the same words) will be
    used to report capabilities of a proxy being declared and an
    existing proxy ;

  - avoid the term "conflicting capabilities" in favor of "overlapping
    capabilities" which is more exact.

  - just report that the same name is reused in case of warnings
diff --git a/src/cfgparse.c b/src/cfgparse.c
index fc333bf..0df66da 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -539,8 +539,8 @@
 			if (!strcmp(curproxy->id, args[1]) &&
 				(rc!=(PR_CAP_FE|PR_CAP_RS) || curproxy->cap!=(PR_CAP_BE|PR_CAP_RS)) &&
 				(rc!=(PR_CAP_BE|PR_CAP_RS) || curproxy->cap!=(PR_CAP_FE|PR_CAP_RS))) {
-				Warning("Parsing [%s:%d]: duplicated proxy '%s' with conflicting capabilities: %s/%s!\n",
-					file, linenum, args[1], proxy_type_str(curproxy), args[0]);
+				Warning("Parsing [%s:%d]: %s '%s' has same name as another %s.\n",
+					file, linenum, proxy_cap_str(rc), args[1], proxy_type_str(curproxy));
 			}
 		}