Replace IntervalTree with Vec

 name                                        before ns/iter  after ns/iter  diff ns/iter   diff %  speedup
 context_new_and_query_location_rc           2,427,320       2,432,182             4,862    0.20%   x 1.00
 context_new_and_query_location_slice        765,873         758,006              -7,867   -1.03%   x 1.01
 context_new_and_query_with_functions_rc     2,993,102       2,959,278           -33,824   -1.13%   x 1.01
 context_new_and_query_with_functions_slice  1,133,112       1,152,324            19,212    1.70%   x 0.98
 context_new_parse_functions_rc              31,235,025      33,387,535        2,152,510    6.89%   x 0.94
 context_new_parse_functions_slice           23,754,161      26,858,657        3,104,496   13.07%   x 0.88
 context_new_parse_lines_rc                  11,725,686      11,711,061          -14,625   -0.12%   x 1.00
 context_new_parse_lines_slice               7,337,852       7,283,802           -54,050   -0.74%   x 1.01
 context_new_rc                              2,207,283       2,162,930           -44,353   -2.01%   x 1.02
 context_new_slice                           613,189         603,892              -9,297   -1.52%   x 1.02
 context_query_location_rc                   728,349         733,083               4,734    0.65%   x 0.99
 context_query_location_slice                721,907         729,294               7,387    1.02%   x 0.99
 context_query_with_functions_rc             4,292,707       1,952,886        -2,339,821  -54.51%   x 2.20
 context_query_with_functions_slice          4,302,388       1,744,765        -2,557,623  -59.45%   x 2.47
 new                                         28,964          27,013               -1,951   -6.74%   x 1.07
 new_unresolved_and_resolve_separate         29,332          26,986               -2,346   -8.00%   x 1.09
 trace_and_resolve_callback                  13,379          11,471               -1,908  -14.26%   x 1.17
 trace_and_resolve_separate                  11,013          9,801                -1,212  -11.01%   x 1.12

For the test `parse_functions_slice`, memory usage increased from 17.4MB to 19.7MB.

Cargo.toml

@@ -18,7 +18,6 @@ travis-ci = { repository = "gimli-rs/addr2line" }
 gimli = { version = "0.19", default-features = false, features = ["read"], git = "https://github.com/gimli-rs/gimli.git", rev = "1b7706bc87938916b4df4cda0c7d1346e938fe86" }
 fallible-iterator = { version = "0.2", default-features = false }
 object = { version = "0.16", default-features = false, features = ["read"], optional = true }
-intervaltree = { version = "0.2", default-features = false }
 smallvec = { version = "1", default-features = false }
 lazycell = "1"
 rustc-demangle = { version = "0.1", optional = true }
@@ -39,7 +38,7 @@ codegen-units = 1
 
 [features]
 default = ["rustc-demangle", "cpp_demangle", "std-object"]
-std = ["gimli/std", "intervaltree/std"]
+std = ["gimli/std"]
 std-object = ["std", "object", "object/std"]
 alloc = ["gimli/alloc"]