Add support fo different ranges in inspect_num(df1, df2)

[cregouby]

and fix #48

── R CMD check results ─────────────────────────────────────────────── inspectdf 0.0.12 ────
Duration: 27.4s

0 errors ✔ | 0 warnings ✔ | 0 notes ✔

R CMD check succeeded

ℹ Testing inspectdf
✔ | F W S  OK | Context
✔ |         7 | helpers                                                                     
✔ |         4 | get_df_names                                                                
✔ |         8 | inspect_cat with grouped dataframes                                         
✔ |        10 | inspect_cat pair of dataframes                                              
✔ |        12 | inspect_cat single dataframe                                                
✔ |        14 | inspect_cor with grouped dataframes [1.1s]                                  
✔ |        11 | inspect_cor with pair dataframes                                            
✔ |        30 | inspect_cor with single dataframe                                           
✔ |         8 | inspect_imb with grouped dataframes                                         
✔ |        10 | inspect_imb pair of dataframes                                              
✔ |         8 | inspect_imb                                                                 
✔ |         8 | inspect_mem with grouped dataframes                                         
✔ |        10 | inspect_mem pair of dataframes                                              
✔ |         5 | inspect_mem                                                                 
✔ |        12 | inspect_na with grouped dataframes                                          
✔ |        10 | inspect_na pair of dataframes                                               
✔ |         5 | inspect_na single dataframe                                                 
✔ |         6 | inspect_num with grouped dataframes                                         
✔ |        18 | inspect_num pair of dataframes [1.5s]                                       
✔ |         9 | inspect_num single dataframes                                               
✔ |        10 | inspect_types pair of dataframes                                            
✔ |         5 | inspect_types single dataframe                                              
✔ |         2 | js_divergence_vec                                                           
✔ |   1    18 | show_plot inspect_cat [2.7s]   
✔ |   1    20 | show_plot inspect_cor [2.6s]       
✔ |        10 | show_plot inspect_imb plots                                                 
✔ |        11 | show_plot inspect_mem                                                       
✔ |        13 | show_plot inspect_na                                                                                                 
✔ |        10 | show_plot inspect_num [2.6s]                                                
✔ |         8 | show_plot inspect_types                                                     
✔ |         1 | inspect_na single dataframe                                                 
✔ |         4 | helpers                                                                     

══ Results ═════════════════════════════════════════════════════════════════════════════════
Duration: 19.7 s

[ FAIL 0 | WARN 2 | SKIP 0 | PASS 317 ]

[RoelVerbelen]

Thanks @cregouby, this solved the issue I was running into with #48.

@alastairrushworth Any chance you could review and merge?