Extract compiled calculation formula and show in result

[nhirokinet]

Currently input formula is directly shown in result, but this should be regenerated from the compile one used in actual calculation.

e.g, input: 2meters+3m*4 output: (2meter+(3meter*4))

Purposes:

• When unit is not the one user desires, users should notice
• When formula has mistake, this information is desired to fix the formula
• In case of bug, users have possibility to notice

[nhirokinet]

There would be better way, closing this issue.