Fixed up debouncer and added some assertions

I moved around where packages are. I couldn't find any evidence of where
other people put them, but for now they are in the `lib/` folder. Other
infrastructure changes are that all the weird includes we need to make
the linter happy are gated behind ifdefs, so they don't mess with
vivado.

I kinda can't believe concurrent assertions work because there's so
little info about them, good to ssee they actually do something

design/audio/audio_buffer.sv

@@ -1,4 +1,6 @@
-`include "sdvd_defs.sv"
+`ifdef VERILATOR
+    `include "sdvd_defs.sv"
+`endif
 import sdvd_defs::SPEED;
 
 //this interfaces with block ram

design/debouncer.sv

@@ -1,27 +1,22 @@
 //NOTE: you should drive this with a slow clock to actually debounce input
-module debouncer(input logic clk, input reset, input source, output wire out);
+module debouncer(input logic clk, input reset, input source, output logic out);
 
 logic pressed;
-assign out = pressed;
 
 always_ff @(posedge clk) begin
     if (reset)
         pressed <= 0;
-    else if (!pressed && source)
-        pressed <= 1;
-    else if (pressed && !source)
-        pressed <= 0;
-    else if (pressed && source)
-        pressed <= 0;
-    else if (!pressed && !source)
+    if (!source) begin
         pressed <= 0;
+        out <= 0;
+    end
+    else
+        if (pressed)
+            out <= 0;
+        else begin
+            pressed <= 1;
+            out <= 1;
+        end
 end
 
-
-//always_ff (@posedge clk) begin
-//
-//end
-
-
-
 endmodule

design/low_freq_clock_gen.sv

@@ -1,4 +1,6 @@
-`include "sdvd_defs.sv"
+`ifdef VERILATOR
+    `include "sdvd_defs.sv"
+`endif
 import sdvd_defs::SPEED;
 // Takes in a 100MHz clock and generates the very low freq signals needed
 // for driving the control logic

design/nexys_a7_top.sv

@@ -1,4 +1,6 @@
-`include "sdvd_defs.sv"
+`ifdef VERILATOR
+    `include "sdvd_defs.sv"
+`endif
 import sdvd_defs::SPEED;
 module nexys_a7_top(
     input logic CLK100MHZ, CPU_RESETN,

design/playback_controller.sv

@@ -9,7 +9,9 @@
  *
  * */
 
-`include "sdvd_defs.sv"
+`ifdef VERILATOR
+    `include "sdvd_defs.sv"
+`endif
 import sdvd_defs::SPEED;
 
 module playback_controller(

design/sdvd_defs.sv

@@ -1,7 +0,0 @@
-`ifndef SDVD_DEFS
-`define SDVD_DEFS
-package sdvd_defs;
-    // Playback speed type
-    typedef logic [3:0] SPEED;
-endpackage
-`endif