notifications at the time of import

[bdolor]

for contextual learning, or just in time learning, add meaningful notification messages at the time of import that:

• ask if wp-quicklatex is activated (depending on whether the book they are importing has equations)
• rendering issues with wp-quicklatex for the first page load will be slower than usual (for image caching)
• some messaging around large file sizes my take a long time.

[bdolor]

doing this in stages... @lucwrite I've done a quick drive-by of one of the three notifications mentioned above via 99838e1. can be modified, depending on the outcome of #57

[lucwrite]

Looks good - A suggestion "Importing a book with Latex equations activate..."

[bdolor]

addressed in 756f2b3

messaging when wp-quicklatex is not activated:

messaging when wp quicklatex is activated: