Move away from deprecated metadata functions in EventLoopGrid
This MR replaces the deprecated functions getMetaDouble() and getMetaString() with the corresponding use of the meta() function in a couple of EventLoopGrid scripts. The functionality should remain the same, but this should get rid of warning messages such as
input_line_159:7:56: warning: 'getMetaDouble' is deprecated: use meta() instead [-Wdeprecated-declarations]