Merge pull request #327 from rattoma/master

Identification and sensitivity fixes
Fix bug in ML forecasting if observables are not included
Fixing bug introduced in ae82c284dcc11714e39a29e11400ee79af8df02e
reporting: @table: vlines
reporting: @table, @graph: require data to be dynSeries, simplify checks
reporting: spacing cleanup
reporting: @vspace
Changed behaviour of @dynDates/display.
Added @dynDates/union function.
Added a routine to convert variable names with underscores into somthing readable by a tex processor.
Deduce tex names from the names of the variables in dynSeries objects.
Make load and save routines for dynSeries objects support tex variable names.
Changed behaviour of @dynSeries/uminus and fixed bug.

 + Prefix variable names with the minus symbol.
 + Set tex member.
Changed copyright year.
Changed behaviour of @dynSeries/ydiff (name  of the variables).

 + Prefix variable names with YDIFF_
 + Prefix tex variable names with \Delta_i with i=nothing, 4, 12 or 52 depending on the frequency.
Added unitary test for @dynSeries/ydiff.
Changed behaviour of @dynSeries/qdiff (name  of the variables).

+ Prefix variable names with QDIFF_
+ Prefix tex variable names with \Delta_i with i=nothing or 3 depending on the frequency.
Changed behaviour of @dynSeries/ygrowth (name  of the variables).

 + Prefix variable names with YGROWTH_
 + Prefix tex variable names with \delta_i with i=nothing, 4, 12  or 52 depending on the frequency.
Changed behaviour of @dynSeries/qgrowth (name  of the variables).

+ Prefix variable names with QGROWTH_
+ Prefix tex variable names with \delta_i with i=nothing or 3 depending on the frequency.
Fixed bug (added missing tex member to extracted variables).