[PD-dev] pd howto errata

Here's errata for the first part of the tutorial on building externals:

change all pd to Pd

change all `` to "

http://iem.at/pd/externals-HOWTO/

change HOWTO to HOW TO

change explain, how to explain how

change pdf(English) to pdf (English)

change pdf(German) to pdf (German)

http://iem.at/pd/externals-HOWTO/node2.html

change windos-plattforms to windows platforms

change pd ist to pd is

change systemdependent to system dependent

change pd supports to to pd supports two

http://iem.at/pd/externals-HOWTO/node3.html

change witha to with a

change messagesystem to message system

change and are therefore are to and are therefore

change functionn to function

remove Das erste Argument ist der symbolische Name der Klasse.

*** explain what order A_DEFFLOAT and A_DEFSYMBOL may appear when defining arguments for object or methods ***

-Jonathan