#54 Tweak for ncurses-6.3 intercafe

[Sergei Trofimovich]

ncuses-6.3 added printf-style function attributes and now makes
it easier to catch cases when user input is used in palce of format
string when built with CFLAGS=-Werror=format-security:

ecasignalview.cpp:360:13:
error: format not a string literal and no format arguments [-Werror=format-security]
360 | mvprintw(r++, 0, bar);
| ~~~~~~~~^~~~~~~~~~~~~

Let's wrap all the missing places with "%s" format.

Attached the patch that fixes build fr this scenario.