Spindle handling refactoring for improved management and configuration of multiple spindles.

NOTE: this is a relatively large change and may have introduced bugs and/or unintended side-effects. Please report any issues!

Added setting $519 for binding spindle encoder to given spindle in multi spindle configurations.

Added machine readable spindle enumeration report, $SPINDLESH.

Increased default value for setting $398 (number of planner blocs) from 35 to 100 for faster laser engraving.
NOTE: the $398 setting value will not change on an upgrade!
NOTE: STM32F103 builds for the 128K flash variants does not have enough free RAM and will keep 35 as the default value.

Increased allowed number of decimal places from 3 to 5 for $10x stepper step/mm settings. Ref. ioSender issue 346.

Added setting $650 for filing system options. Ref. issue 397.
Currently the following bits are available (depending on the configuration):
0 - Auto mount SD card on startup (1).
1 - Do not add littlefs files when listing the root directory (2).

Added build option for lathe UVW mode.
When enabled UVW words can be used to command relative moves for XYZ without switching to relative mode with G91.
NOTE: This permanently sets lathe mode and disables the $32 mode setting.

There are signature changes to some spindle, ioports enumeration and VFS filing system mount functions.

Added events to allow plugin code to handle tool table data, possibly stored on a SD card.

driver_opts.h

@@ -159,7 +159,15 @@
 #endif
 
 #ifndef SPINDLE_SYNC_ENABLE
-#define SPINDLE_SYNC_ENABLE 0
+#define SPINDLE_SYNC_ENABLE     0
+#endif
+
+#ifndef SPINDLE_ENCODER_ENABLE
+#if SPINDLE_SYNC_ENABLE
+#define SPINDLE_ENCODER_ENABLE  1
+#else
+#define SPINDLE_ENCODER_ENABLE  0
+#endif
 #endif
 
 #ifndef TRINAMIC_ENABLE
@@ -213,10 +221,6 @@
 #define PPI_ENABLE          0
 #endif
 
-#ifndef STEP_INJECT_ENABLE
-#define STEP_INJECT_ENABLE  0
-#endif
-
 #if EMBROIDERY_ENABLE
 #if defined(SDCARD_ENABLE) && SDCARD_ENABLE == 0
 #undef SDCARD_ENABLE
@@ -226,6 +230,7 @@
 #endif
 #endif
 
+// TODO: remove?
 #ifndef VFD_SPINDLE
 #if VFD_ENABLE
 #define VFD_SPINDLE         1
@@ -234,6 +239,93 @@
 #endif
 #endif
 
+#ifndef SPINDLE0_ENABLE
+  #if VFD_ENABLE
+    #define SPINDLE0_ENABLE VFD_ENABLE
+    #if N_SPINDLE > 1 && !defined(SPINDLE1_ENABLE)
+      #define SPINDLE1_ENABLE SPINDLE_PWM0
+    #endif
+  #else
+    #define SPINDLE0_ENABLE SPINDLE_PWM0
+  #endif
+#endif
+
+#ifndef SPINDLE1_ENABLE
+#define SPINDLE1_ENABLE     0
+#endif
+
+#ifndef SPINDLE2_ENABLE
+#define SPINDLE2_ENABLE     0
+#endif
+
+#ifndef SPINDLE3_ENABLE
+#define SPINDLE3_ENABLE     0
+#endif
+
+#if SPINDLE0_ENABLE == SPINDLE_ALL
+#define SPINDLE_ENABLE SPINDLE_ALL
+#else
+#define SPINDLE_ENABLE ((1<<SPINDLE0_ENABLE)|(1<<SPINDLE1_ENABLE)|(1<<SPINDLE2_ENABLE)|(1<<SPINDLE3_ENABLE))
+#endif
+
+// Driver spindle 0
+
+#if SPINDLE_ENABLE & ((1<<SPINDLE_PWM0)|(1<<SPINDLE_PWM0_NODIR)|(1<<SPINDLE_ONOFF0)|(1<<SPINDLE_ONOFF0_DIR))
+#define DRIVER_SPINDLE_ENABLE       1
+#else
+#define DRIVER_SPINDLE_ENABLE       0
+#endif
+
+#if SPINDLE_ENABLE & ((1<<SPINDLE_PWM0)|(1<<SPINDLE_ONOFF0_DIR))
+#define DRIVER_SPINDLE_DIR_ENABLE   1
+#else
+#define DRIVER_SPINDLE_DIR_ENABLE   0
+#endif
+
+#if SPINDLE_ENABLE & ((1<<SPINDLE_PWM0)|(1<<SPINDLE_PWM0_NODIR))
+#define DRIVER_SPINDLE_PWM_ENABLE  1
+#define DRIVER_SPINDLE_NAME "PWM"
+#else
+#define DRIVER_SPINDLE_PWM_ENABLE  0
+#if DRIVER_SPINDLE_ENABLE
+#define DRIVER_SPINDLE_NAME "Basic"
+#endif
+#endif
+
+// Driver spindle 1
+
+#if SPINDLE_ENABLE & ((1<<SPINDLE_PWM1)|(1<<SPINDLE_PWM1_NODIR)|(1<<SPINDLE_ONOFF1)|(1<<SPINDLE_ONOFF1_DIR))
+#define DRIVER_SPINDLE1_ENABLE       1
+#else
+#define DRIVER_SPINDLE1_ENABLE       0
+#endif
+
+#if SPINDLE_ENABLE & ((1<<SPINDLE_PWM1)|(1<<SPINDLE_ONOFF1_DIR))
+#define DRIVER_SPINDLE1_DIR_ENABLE   1
+#else
+#define DRIVER_SPINDLE1_DIR_ENABLE   0
+#endif
+
+#if SPINDLE_ENABLE & ((1<<SPINDLE_PWM1)|(1<<SPINDLE_PWM1_NODIR))
+#define DRIVER_SPINDLE1_PWM_ENABLE  1
+#define DRIVER_SPINDLE1_NAME "PWM"
+#else
+#define DRIVER_SPINDLE1_PWM_ENABLE  0
+#if DRIVER_SPINDLE1_ENABLE
+#define DRIVER_SPINDLE1_NAME "Basic"
+#endif
+#endif
+
+//
+
+#ifndef VFD_ENABLE
+  #if SPINDLE_ENABLE & ((1<<SPINDLE_HUANYANG1)|(1<<SPINDLE_HUANYANG2)|(1<<SPINDLE_GS20)|(1<<SPINDLE_YL620A)|(1<<SPINDLE_MODVFD)|(1<<SPINDLE_H100)|(1<<SPINDLE_NOWFOREVER))
+    #define VFD_ENABLE 1
+  #else
+    #define VFD_ENABLE 0
+  #endif
+#endif
+
 #define MODBUS_RTU_ENABLED     0b001
 #define MODBUS_RTU_DIR_ENABLED 0b010
 #define MODBUS_TCP_ENABLED     0b100
@@ -251,10 +343,12 @@
 #endif
 #endif
 
-#if !VFD_SPINDLE || N_SPINDLE > 1
-#define DRIVER_SPINDLE_ENABLE  1
-#else
-#define DRIVER_SPINDLE_ENABLE  0
+#ifndef STEP_INJECT_ENABLE
+  #if SPINDLE_ENABLE & (1<<SPINDLE_STEPPER)
+    #define STEP_INJECT_ENABLE 1
+  #else
+    #define STEP_INJECT_ENABLE 0
+  #endif
 #endif
 
 #ifndef QEI_ENABLE