Adding support for the bazel build system

This includes the libraries and examples. The correct implementation
should automatically be configured depending on the platform.

.gitignore

@@ -32,3 +32,5 @@ doc/html
 ipch
 Debug
 Release
+
+bazel-*

.travis.yml

@@ -7,4 +7,4 @@ install:
   - source setup.bash
 script:
   - mkdir build && cd build && cmake .. -DPYTHON_EXECUTABLE=$(which python2) && make && make tests && make run_tests
-  - catkin_test_results .
+  - catkin_test_results .

BUILD

@@ -0,0 +1,65 @@
+load("@rules_cc//cc:defs.bzl", "cc_library", "cc_binary")
+
+cc_library(
+    name = "serial",
+    deps = [
+        ":serial_facade",
+        ":common_impl",
+    ] + select({
+        ":windows": [":windows_impl"],
+        ":linux": [":linux_impl"],
+        ":macos": [":unix_impl"],
+    }),
+    visibility = ["//visibility:public"],
+)
+
+cc_library(
+    name = "serial_facade",
+    hdrs = glob(["**/*.h"]),
+    includes = ["include"],
+)
+
+cc_library(
+    name = "windows_impl",
+    srcs = [
+        "src/impl/list_ports/list_ports_win.cc",
+        "src/impl/win.cc",
+    ],
+    deps = [":serial_facade"],
+)
+
+cc_library(
+    name = "linux_impl",
+    srcs = [
+        "src/impl/list_ports/list_ports_linux.cc",
+        "src/impl/unix.cc",
+    ],
+    deps = [":serial_facade"],
+)
+
+cc_library(
+    name = "common_impl",
+    srcs = ["src/serial.cc"],
+    deps = [":serial_facade"],
+)
+
+cc_binary(
+    name = "example",
+    srcs = ["examples/serial_example.cc"],
+    deps = [":serial"],
+)
+
+config_setting(
+    name = "windows",
+    constraint_values = ["@platforms//os:windows"],
+)
+
+config_setting(
+    name = "linux",
+    constraint_values = ["@platforms//os:linux"],
+)
+
+config_setting(
+    name = "macos",
+    constraint_values = ["@platforms//os:macos"],
+)