Implement Goto Definition Filters

[ismell]

Now that we are getting better syntax definitions and to make sublimehq/Packages#1861 a reality, I think we need to have the ability to filter the Goto Definition list.

Using the C syntax definition below

/* SYNTAX TEST "Packages/C++/C.sublime-syntax" */

struct device {
/*     ^^^^^^ meta.struct.c entity.name.struct.c */
  unsigned int address;
/*             ^^^^^^^ entity.name.member.c */
};

struct xhci {
/*     ^^^^ meta.struct.c entity.name.struct.c */
  struct device device;
/*       ^^^^^^ support.type.c */
/*              ^^^^^^ entity.name.member.c */
  unsigned int ports;
/*             ^^^^^ entity.name.member.c */
};

struct sdhci {
/*     ^^^^^ meta.struct.c entity.name.struct.c */
  struct device device;
/*       ^^^^^^ support.type.c */
/*              ^^^^^^ entity.name.member.c */
  unsigned int ports;
/*             ^^^^^ entity.name.member.c */
};

struct xhci xhci;
/*     ^^^^ support.type.c */
/*          ^^^^ entity.name.variable.global.c */

int main(void) {
  struct device *device = &xhci.device;
/*       ^^^^^^ support.type.c */
/*               ^^^^^^ entity.name.variable.local.c */
/*                         ^^^^ variable.other.c */
/*                              ^^^^^^ variable.other.member.c */

  device->address = 0x100;
/*^^^^^^ variable.other.c */
/*        ^^^^^^^ variable.other.member.c */

  return 0;
}

The scopes are targeted enough that we should be able to make Goto Definition pretty accurate by applying a scope filter to the definition list depending on the scope of the source.

Source	Filter
support.type.c	entity.name - entity.name.member - entity.name.variable
variable.other.c	entity.name.variable
variable.other.member.c	entity.name.member

In the case that no match is found with the filters applied, the original behavior of not having a filter should be used. This way if you have a struct name in a comment or string it will still allow you to navigate, but with more noise.

Today, if I push Goto Definition while my cursor is on device of support.type.c, it will return three entries, the declaration and the two members. This makes the list very noisy when dealing with a very large code base (i.e., Linux Kernel).

An added bonus would be to have some kind of filter so when you do Goto Definition on device of variable.other.c It only shows the entity.name.variable.local within the same meta.function.c. This way you don't get local variables for other functions. The C syntax definition does not currently label local variables as entity.name.variable.local to avoid all the noise.