CURA-4526 Delete LayerView plugin because it will be replaced with the

SimulationView.
This commit also adapts the code in order to accept the messages coming
from the engine, with information about feedrates and line thicknesses.
Add also some changes in the GCodeReader that reads feedrates and
line thickness from the gcode file.

plugins/CuraEngineBackend/Cura.proto

@@ -61,6 +61,8 @@ message Polygon {
     Type type = 1; // Type of move
     bytes points = 2; // The points of the polygon, or two points if only a line segment (Currently only line segments are used)
     float line_width = 3; // The width of the line being laid down
+    float line_thickness = 4; // The thickness of the line being laid down
+    float line_feedrate = 5; // The feedrate of the line being laid down
 }
 
 message LayerOptimized {
@@ -82,6 +84,8 @@ message PathSegment {
     bytes points = 3; // The points defining the line segments, bytes of float[2/3] array of length N+1
     bytes line_type = 4; // Type of line segment as an unsigned char array of length 1 or N, where N is the number of line segments in this path
     bytes line_width = 5; // The widths of the line segments as bytes of a float array of length 1 or N
+    bytes line_thickness = 6; // The thickness of the line segments as bytes of a float array of length 1 or N
+    bytes line_feedrate = 7; // The feedrate of the line segments as bytes of a float array of length 1 or N
 }