Add a way to disable pipes for the Wine host

For some reason ujam plugins (and other plugins made with the Gorilla
Engine, like the LoopCloud plugins) will throw a `JS_EXEC_FAILED` error
when trying to load the plugin while either of the STDOUT or STDERR
streams is pointing to a pipe. Simply redirecting the output to a file
fixes this. By default we'll write the output to
`<temporary_directory>/yabridge-plugin-output.log`, but you can also set
the new `disable_pipes` option to `"/dev/null"` to completely throw away
all output.

This addresses #47.

src/common/configuration.cpp

@@ -24,6 +24,8 @@
 #include <toml++/toml.h>
 #include <fstream>
 
+#include "utils.h"
+
 namespace fs = boost::filesystem;
 
 Configuration::Configuration() noexcept {}
@@ -84,6 +86,21 @@ Configuration::Configuration(const fs::path& config_path,
                 } else {
                     invalid_options.push_back(key);
                 }
+            } else if (key == "disable_pipes") {
+                // This option can be either enabled or disable with a boolean,
+                // or it can be set to an absolute path
+                if (const auto parsed_value = value.as_boolean()) {
+                    if (*parsed_value) {
+                        disable_pipes = get_temporary_directory() /
+                                        "yabridge-plugin-output.log";
+                    } else {
+                        disable_pipes = std::nullopt;
+                    }
+                } else if (const auto parsed_value = value.as_string()) {
+                    disable_pipes = parsed_value->get();
+                } else {
+                    invalid_options.push_back(key);
+                }
             } else if (key == "editor_double_embed") {
                 if (const auto parsed_value = value.as_boolean()) {
                     editor_double_embed = parsed_value->get();