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>
Clear settings on department deletion

Clear ticket routing settings on topic, email or filter tables on department
deletion.
Merge pull request #792 from protich/issue/cleardeptsetting

Clear settings on department deletion

Reviewed-By: Jared Hancock <jared@osticket.com>
Show more dropdown for users with edit permission

Users with edit permission should be able to change ticket owner in line.
Merge pull request #799 from protich/issue/change-owner

Show more drop down for users with edit permission

Reviewed-By: Jared Hancock <jared@osticket.com>
Merge remote branch 'upstream/develop' into develop-next