Multiple MCS dialog improvements

[Paulocracy]

This PR aims to fix the following MCS dialog issues:

• The rusty left-hand-side parse is now removed, so that the issues with parsing seceral mathematical operators do not occur anymore.
• As a replacement, I expanded the list comprehension of MCSDialog's parsing the desired and target regions such that, if an error occurs, a pop-up window appears telling the user in which target or desired region the error occurs. Also, TypeErrors are now caught (this was missing up to now but could happen, if, e.g., a user types in values such as "1.2d").
• Furthermore, full reaction name complemetions (not only for the first reaction) as in the StrainDesign dialog was added through the usage of QComplReceivLineEdit from cnapy.utils. Unfortunately, the checker which automatically colors a line red if the equation is wrong doesn't work here as this checker also demands a ">=" or "<=" and cannot work with "/".
• Finally, as a clunky fix to allow the usage of "-", " - " occurreces in the left hand sides are replaces with " + -", which somehow works with the MCS parser here.

Any ideas, especially regarding a higher level of congruence with StrainDesign, are very welcome :-)

[axelvonkamp]

@Paulocracy Can you check that the update to optlang_enumerator 0.0.9 fixes the parsing problem?