Migrate get_usage_name() at profile.c to get_cylinder_segment_usage_string() at helpers.h

Trying to follow the lead on get_string() functions: they should be at helpers.h and qt-gui.cpp.

Signed-off-by: Rodrigo Severo <rodrigo@fabricadeideias.com>
profile.c helpers moved to profile.c

Signed-off-by: Rodrigo Severo <rodrigo@fabricadeideias.com>
Always use cyl_index for indexing cylinders,

Signed-off-by: Rodrigo Severo <rodrigo@fabricadeideias.com>
Always use cyl_index for indexing cylinders,

Signed-off-by: Rodrigo Severo <rodrigo@fabricadeideias.com>
Trying to show pressure plots

Signed-off-by: Rodrigo Severo <rodrigo@fabricadeideias.com>