v1.0.4

• Increased speed when setting max_diff_peak2mean = 0:
  In this special case there is no need to use a time-consuming iterative approach to align peaks. Instead, peaks are simply sorted in temporal order of absolute retention time values. This is implemented in two steps. (1) Across all samples, unique retention times are extracted, sorted in increasing temporal order and written to a template data frame (number of rows equals number of unique retention times). (2) For each sample, peaks are matched to the corresponding row of the template data frame. Note, in this situation only the parameter min_diff_peak2peak determines which peaks are considered as potentially homologous.
• Small bug fixed that caused problems when plotting x-axis labels in gc_heatmap.
• Added a test for detecting inconsistently ordered retention times. In general, retention times should appear in increasing temporal order. If this assumption is violated, retention times are reordered and a warning message is shown.