Fix user-facing and non-user-facing typos

Found via `codespell v2.1.dev0`

doc/src/api_overview.dox

@@ -112,7 +112,7 @@ Many of the tests in the /tests directory of the PortAudio distribution implemen
 
 @subsection read_write_io_method The Read/Write I/O Method
 
-As an alternative to the callback I/O method, PortAudio provides a synchronous read/write interface for acquiring and playing audio. This can be useful for applications that don't require the lowest possibly latency, or don't warrant the increased complexity of synchronising with an asynchronous callback funciton. This I/O method is also useful when calling PortAudio from programming languages that don't support asynchronous callbacks. 
+As an alternative to the callback I/O method, PortAudio provides a synchronous read/write interface for acquiring and playing audio. This can be useful for applications that don't require the lowest possibly latency, or don't warrant the increased complexity of synchronising with an asynchronous callback function. This I/O method is also useful when calling PortAudio from programming languages that don't support asynchronous callbacks. 
 
 To open a Stream in read/write mode you pass a NULL stream callback function pointer to Pa_OpenStream().
 

doc/src/tutorial/compile_cmake.dox

@@ -23,7 +23,7 @@ The "-G" option specifies the type of build metadata which will be generated. Yo
 
 "make install" should install the same set of files that are installed using the usual configure script included with PortAudio along with a few extra files (similar to pkg-config metadata files) which make it easier for other CMake projects to use the installed libraries.
 
-On Windows, you can use CMake to generate Visual Studio project files which can be used to create the PortAudio libraries. The following serves as an example (and should be done from a directory outside the PortAudio tree) which will create Visual Studio 2015 project files targetting a 64-bit build:
+On Windows, you can use CMake to generate Visual Studio project files which can be used to create the PortAudio libraries. The following serves as an example (and should be done from a directory outside the PortAudio tree) which will create Visual Studio 2015 project files targeting a 64-bit build:
 
     C:\PABUILD> cmake {portaudio path} -G "Visual Studio 14 2015 Win64"
 

doc/src/tutorial/compile_linux.dox

@@ -47,7 +47,7 @@ On some systems you may need to use:
 cp /usr/local/lib/libportaudio.a /YOUR/PROJECT/DIR
 @endcode
 
-You may also need to copy portaudio.h, located in the include/ directory of PortAudio into your project. Note that you will usually need to link with the approriate libraries that you used, such as ALSA and JACK, as well as with librt and libpthread. For example:
+You may also need to copy portaudio.h, located in the include/ directory of PortAudio into your project. Note that you will usually need to link with the appropriate libraries that you used, such as ALSA and JACK, as well as with librt and libpthread. For example:
 
 @code
 gcc main.c libportaudio.a -lrt -lm -lasound -ljack -pthread -o YOUR_BINARY

doc/src/tutorial/start_stop_abort.dox

@@ -10,7 +10,7 @@ PortAudio will not start playing back audio until you start the stream. After ca
     if( err != paNoError ) goto error;
 @endcode
 
-You can communicate with your callback routine through the data structure you passed in on the open call, or through global variables, or using other interprocess communication techniques, but please be aware that your callback function may be called at interrupt time when your foreground process is least expecting it. So avoid sharing complex data structures that are easily corrupted like double linked lists, and avoid using locks such as mutexs as this may cause your callback function to block and therefore drop audio. Such techniques may even cause deadlock on some platforms.
+You can communicate with your callback routine through the data structure you passed in on the open call, or through global variables, or using other interprocess communication techniques, but please be aware that your callback function may be called at interrupt time when your foreground process is least expecting it. So avoid sharing complex data structures that are easily corrupted like double linked lists, and avoid using locks such as mutexes as this may cause your callback function to block and therefore drop audio. Such techniques may even cause deadlock on some platforms.
 
 PortAudio will continue to call your callback and process audio until you stop the stream. This can be done in one of several ways, but, before we do so, we'll want to see that some of our audio gets processed by sleeping for a few seconds. This is easy to do with Pa_Sleep(), which is used by many of the examples in the patests/ directory for exactly this purpose. Note that, for a variety of reasons, you can not rely on this function for accurate scheduling, so your stream may not run for exactly the same amount of time as you expect, but it's good enough for our example.