Version Control With Subversion Source

Update a screen capture of 'svn help import'.

* cho04: fix outdated warning.

"Ma Subversion" changed in "Subversion, tuttavia," just to enhance readability;
replaced "gente" with "utenti" to be more precise;
In paragraph svn.preface.howread changed everything from second person to third person plus style changes;
In paragraph svn.preface.conventions fixed title capitalization and a couple of translations
In paragraph svn.preface.icons translated title and minor changes;
In paragraph svn.preface.organization replaced 'guida per un inizo rapido' with 'guida rapida', fixed use of english
terms instead of their translation, and style enhancements;
Translation choices enhancing italian style and correctness until the end of chapter.
Minor style changes

* src/en/book/ch07-customizing-svn.xml
Describe the merge-tool-cmd option, and try to refer to diff3-cmd as
a 3-way differencing tool (instead of as a merge tool), to avoid
confusion.

* src/en/book/ch03-advanced-topics.xml
* src/en/book/ch07-customizing-svn.xml
Go nuts, documenting the undocumented runtime configuration options.
In the process, generalize some stuff about using external text
editors.

* src/en/book/ch03-advanced-topics.xml
Add some notes about how binariness effects property setting.

* src/en/book/ch05-repository-admin.xml
Describe limitations of the dumpfile format in terms of data
transferred. (For ticket #94).

* src/en/book/ch03-advanced-topics.xml
For ticket #69, describe what "file patterns" are, and what the basic
supported syntax is.

Fix a few typos.

Patches by Arfrever Frehtes Taifersar Arahesis <arfrever.fta@...>.

* src/en/book/ch09-reference.xml,
src/en/book/ch06-server-configuration.xml: Fix typppos.

Agreed translation of the sentence: 'has long been the tool of choice for version control.And rightly so.'
now is:
'è stato a lungo e giustamente lo strumento preferito'