feat: add support for the SDK server

With this change, the gptscript SDK server will be fork/exec-ed instead
of fork/exec-ing for every gptscript command. This produces enhancements
with daemons in gptscript.

This change also intentionally removes support for browser-based
applications.

Author: thedadams

README.md

@@ -18,8 +18,8 @@ running `npm install`.
 
 ## Usage
 
-To use the module and run gptscripts, you need to first set the OPENAI_API_KEY environment variable to your OpenAI API
-key.
+To use the module and run gptscripts, you need to first set the `OPENAI_API_KEY` environment variable to your OpenAI API
+key. You can also set the `GPTSCRIPT_BIN` environment variable to change the execution of the gptscripts.
 
 To ensure it is working properly, you can run the following command:
 
@@ -31,11 +31,10 @@ You will see "Hello, World!" in the output of the command.
 
 ## Client
 
-There are currently a couple "global" options, and the client helps to manage those. A client without any options is
-likely what you want. However, here are the current global options:
-
-- `gptscriptURL`: The URL (including `http(s)://) of an "SDK server" to use instead of the fork/exec model.
-- `gptscriptBin`: The path to a `gptscript` binary to use instead of the bundled one.
+The client allows the caller to run gptscript files, tools, and other operations (see below). There are currently no
+options for this singleton client, so `new gptscript.Client()` is all you need. Although, the intention is that a
+single client is all you need for the life of your application, you should call `close()` on the client when you are
+done.
 
 ## Options
 
@@ -45,7 +44,6 @@ None of the options is required, and the defaults will reduce the number of call
 - `disableCache`: Enable or disable caching, default (true)
 - `cacheDir`: Specify the cache directory
 - `quiet`: No output logging
-- `chdir`: Change current working directory
 - `subTool`: Use tool of this name, not the first tool
 - `workspace`: Directory to use for the workspace, if specified it will not be deleted on exit
 
@@ -64,6 +62,7 @@ async function listTools() {
     const client = new gptscript.Client();
     const tools = await client.listTools();
     console.log(tools);
+    client.close()
 }
 ```
 
@@ -83,6 +82,8 @@ async function listModels() {
         models = await client.listModels();
     } catch (error) {
         console.error(error);
+    } finally {
+        client.close()
     }
 }
 ```
@@ -102,6 +103,8 @@ async function version() {
         console.log(await client.version());
     } catch (error) {
         console.error(error);
+    } finally {
+        client.close()
     }
 }
 ```
@@ -124,6 +127,8 @@ try {
     console.log(await run.text());
 } catch (error) {
     console.error(error);
+} finally {
+    client.close();
 }
 ```
 
@@ -146,6 +151,8 @@ async function execFile() {
         console.log(await run.text());
     } catch (e) {
         console.error(e);
+    } finally {
+        client.close();
     }
 }
 ```
@@ -189,6 +196,8 @@ async function streamExecFileWithEvents() {
         await run.text();
     } catch (e) {
         console.error(e);
+    } finally {
+        client.close();
     }
 }
 ```
@@ -236,6 +245,8 @@ async function streamExecFileWithEvents() {
         }
     } catch (e) {
         console.error(e);
+    } finally {
+        client.close();
     }