clean up imports and reorganize the ssd bits into a graphics mod

Cargo.toml

@@ -21,7 +21,7 @@ max-usb-power = []
 wokwi = ["max-usb-power"]
 mpu = ["dep:mpu6050-dmp"]
 gps = ["dep:nmea"]
-oled = ["dep:ssd1306", "dep:embedded-graphics"]
+oled = ["dep:ssd1306"]
 demo = []
 
 [dependencies]
@@ -77,7 +77,7 @@ esp-wifi = { version = "0.15.0", optional = true, features = [
   "ble"
 ] }
 bleps =  { git = "https://github.com/bjoernQ/bleps", optional = true, package = "bleps", rev = "a5148d8ae679e021b78f53fd33afb8bb35d0b62e", features = [ "macros", "async"] }
-embedded-graphics = { version = "0.8.1", features = ["nalgebra_support"], optional = true}
+embedded-graphics = { version = "0.8.1", features = ["nalgebra_support"] }
 ssd1306 = { version = "0.10.0", features = ["async"], optional = true }
 
 # Sensors