TextSearch: way speeder by using xargs + grep

* Previously, each file was starting a shell to run grep
command on it. Very suboptimal performance, big overhead.
* Now a thread write each file path to xargs input,
while another start xargs, let it distribute files on
grep processes (one per cpu) and collect results asap.
* This bring results way faster than previously.
* Rename Escape Text setting into Regular Expression, as
name was more after shell workaround than after function.
* While it doesn't use a native text searching, by
reusing both grep and xargs power, it answer the main
issue with #9529.

Revert "TextSearch: use BString-based searching instead of Grep-based."

This reverts commit 1e9f5f5be4c8419c2085f51c78c9ac02ef13377b.
As per discussion on the ML.

TextSearch: use BString-based searching instead of Grep-based.

Huge performance improvement. Fixes #9529.

TextSearch: normalize copyright headers.

TextSearch: trim trailing whitespace.

Refactoring
* FileIterator is now a mostly abstract interface
* FolderIterator is the currently only implementation (there could be
MessageIterator for an even better separation, which would read the top
level search folders from the BMessage with the selected poses, but it
would mostly use the same code for traversing the subfolders anyways so I
left that for the time being.)
* The Grepper and FolderIterator now copy the current settings from the Model
at instantiation. Since they run in a separate thread and the Model may
actually be changed from the Window thread, I think this is just a cleaner
and more safe solution.
* Cleanup here and there.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@26786 a95241bf-73f2-0310-859d-f6bbb57e9c96

Refactored a new class FileIterator from Grepper that will make adding
node monitoring easier. Also, FileIterator will be split to make the code
cleaner with regards to folder or selection mode.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@26752 a95241bf-73f2-0310-859d-f6bbb57e9c96

Moved TextSearch to apps folder, since it's actually a regular app.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@26738 a95241bf-73f2-0310-859d-f6bbb57e9c96

Revert "TextSearch: use BString-based searching instead of Grep-based."

This reverts commit 1e9f5f5be4c8419c2085f51c78c9ac02ef13377b.
As per discussion on the ML.

TextSearch: use BString-based searching instead of Grep-based.

Huge performance improvement. Fixes #9529.

TextSearch: normalize copyright headers.

TextSearch: trim trailing whitespace.

Refactoring
* FileIterator is now a mostly abstract interface
* FolderIterator is the currently only implementation (there could be
MessageIterator for an even better separation, which would read the top
level search folders from the BMessage with the selected poses, but it
would mostly use the same code for traversing the subfolders anyways so I
left that for the time being.)
* The Grepper and FolderIterator now copy the current settings from the Model
at instantiation. Since they run in a separate thread and the Model may
actually be changed from the Window thread, I think this is just a cleaner
and more safe solution.
* Cleanup here and there.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@26786 a95241bf-73f2-0310-859d-f6bbb57e9c96

Refactored a new class FileIterator from Grepper that will make adding
node monitoring easier. Also, FileIterator will be split to make the code
cleaner with regards to folder or selection mode.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@26752 a95241bf-73f2-0310-859d-f6bbb57e9c96

Moved TextSearch to apps folder, since it's actually a regular app.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@26738 a95241bf-73f2-0310-859d-f6bbb57e9c96