Relax detection of images for strip detection

It is perfectectly fine to have an image cited in an HTML body similar to:

<img width=909 height=302 src=cid:image002.jpg@01CF5426.BF5A72A0 alt=image>

Which may or may not have quoted @src attribute, and may very well have an
at sign (@) somewhere in the attribute text. The previous regular expression
would not match such a @src attribute.
validation: Fixup a few email address validations
Fixup merging of email recipients

This stems from a confusing similarity between the + operator for arrays
and array_merge() in php. Adding arrays will ignore items in the RHS where
keys are present in the LHS. Therefore, when adding numerically indexed
arrays together, only items on the RHS that have a key higher than the
greatest key on the LHS will be included.
oops: Don't crash when sending fatal alert email
html: Avoid corrupting quoted style attributes

For instance, current this style we be converted as
```
<span style="font-family:'courier new';">
```
to
```
<span style="font-family:&quot;">
```

Also discard Microsoft Office specific style attributes such as `mso-list`
and friends
ui: Fixup unnecessary extra spacing in thread body
html: Trim space around `;` in @style attributes
Merge pull request #784 from greezybacon/issue/html-style-cleanup

html: Avoid corrupting quoted style attributes

Reviewed-By: Peter Rotich <peter@osticket.com>
Merge pull request #785 from greezybacon/issue/thread-body-odd-styles

ui: Fixup unnecessary extra spacing in thread body

Reviewed-By: Peter Rotich <peter@osticket.com>
Provide failsafe for a client's name

It is possible that a recipient received and processed by the system may not
have a name set. In that case, the email mailbox should be used. As a
failsafe, avoid crashing if the User::save() should fail.
Don't clobber custom data for new clients
Add import feature to user directory and organization
Fixup user import via cli
orm: Make __get() and get() consistent
Clear settings on department deletion

Clear ticket routing settings on topic, email or filter tables on department
deletion.
Add concept of quick notes for users and organizations
Fixup user view dialog on ticket view page
pjax: Use PJAX between sections

This will simplify where PJAX needs to be disabled by simply including the
navigation as part of the PJAX response.
Fallback to client email display on user directory
Simplify header detection logic with outdent